Hey, I just graduated with a degree in Engineering Physics and I did a variety of drugs throughout my education so maybe I can help with your desire for high achievement.
Mushrooms are my favourite drug and they have always had a definite positive effect on my life. I was growing them in uni and taking them weekly at one point and they never affected my academics. I don't believe I have ever got any negative side effects from mushrooms or acid... if anything they motivate me and allow me to realize my true potential. You don't want to be distracted by too many crazy trips while you're in school though. It is up to you to decide how often you should use these drugs but I would recommend once a month at most. By the way, looking back on myself before I ate all the mushrooms and acid... I am SO different now. I spend a lot more time alone, being mainly interested in the inner working of my Self. I'm not selfish, it just doesn't make sense to me to be around people who are not spiritually oriented as they bring me back down to where I used to be, which isn't where I am now. There is no going back. So I'm just really selective about who I enjoy hanging around. I have lost touch with a lot of people I used to be hang with all the time, but I totally think that this was all in my best interests.
As for pot, I was stoned 24/7 throughout my degree, for exams and all. This had a negative effect on my electives which required more memory work than physics or engineering, because my memory is fried when I'm stoned. At the time I thought it was making me smarter - it was definately putting a strange twist on the way I came to understand reality in terms of mathematics anyway. My mathematical logic has never been affected by pot smoking, but it wasn't made better by it either. I would highly recommend ceasing habitual smoking before you get too deep into it, A LOT of really smart people end up smoking huge amounts of pot in university but after going through it I would HIGHLY (no pun intended) advise not to get caught up going to lectures and stuff stoned day in day out. It will be tempting because it makes learning about technology pretty awesome and there is nobody around to tell you not to get high all day. It is a great activity for stress relief though so definately include it in your life - I would recommend blazing at the end of each day. When you are in school is the ideal time in your life to be a stoner anyway - you probably won't be able to get away with it afterwards so keep that in mind.
As for alcohol - it's moderation or retardation. I have noticed many of my friends become dumbed down by abusing it. Alcohol is neurotoxic, and it totally wrecks your body. Many people abuse alcohol to all hell in university, and I definately did as well at times. In first year I was getting drunk basically more nights than I wasn't, and I wasn't suffering hangovers or big problems yet. In 2nd year, I had developed severe cognitive deficits and anxiety and depression from this alcohol use, not to mention hangovers from HELL. I continued getting fucked 3 nights a week religiously, and I was such a wreck I consider this the lowest point of my life. I recovered from all this shit before 3rd year, rarely drank and got my shit together, did a lot better and enjoyed the experience a lot more. If you party less, you will have a better time when you party. Partying is a part of the whole experience so I would say just party once a week or you might go crazy with all the work (1st year shouldn't be too much).
As for MDMA - I think it is a real shame that you discovered MDMA at such a young age. I was lucky to only discover it my very last semester in 4th year. I did it a fair amount and had the most fun I have ever had in my life. It was a really special time of my life and I wouldn't take back those times for anything. I would recommend getting the fuck off MDMA until you are near the end of your degree, and then going balls-out raving as a grand finale to the whole experience. If you continue to use MDMA after having done it a fair amount at a young age, you may get FUCKED from it. It can be the death of you, and you won't catch on to the side effects until it's too late. Seriously. Trust me, I know how much fun it is. It is so much fun that it is very dangerous and it sounds like it is perhaps beginning to screw with your enjoyment of life without it. You must make MDMA a very special occasion, a couple-times-a-year sort of thing, and you would be a fool to keep using it now, you need a long break. It can make you retarded. And test your pills if you don't do that - you don't want to be taking any shit that isn't pure MDMA.
Whenever I think of a teenager doing MDMA I am distraught - being a teenager is easy and awesome, why do you have to fuck with hard drugs? The next 4 years of your life will be a wonderful journey of self discovery and you shouldn't be fucking with MDMA until you have fully matured. By the way, no matter how mature you think you presently are, you arn't. no teenager is - you sound like you are advanced for your age but you will doubtlessly grow into yourself over the next few years. You will be able to fully appreciate MDMA and respect it and enjoy it moreso later in life. If you do too much of it now, you arn't going to be able to keep doing it when you are in your 20's and you will definately regret it. Twice a month or even once a month is WAY too much in my opinion, regardless of people on here who say they roll once a month and are fine. Eventually your body will just say no more. I can't handle it more than a couple times a year, and I was all for it for the first while.
The very fact that you have developed a tolerance to pills means that your sober consciousness is being affected. Your brain does not respond to the drug like it once did because it has changed. This is probably due to reversible receptor downregulation. I truly think that if I had discovered MDMA at your age, I would not be who I am today. Like others have said, you really gotta keep an eye out for addiction. Addiction creeps right up on you, I never would have thought myself an addict, and it is HORRIBLE. And my only addiction is to pot (you can get hooked on anything)... it is a severe one.
And by the way - I was getting 99's in high school physics, chemistry, and math courses. I had a B average in university, and I consider myself extremely intelligent. Physics is harder than chemistry though so you should be able to own it without too much trouble. Expect to be challenged. Have fun, exercise moderation, and you should excel.