You took XR's that was your mistake...
XR's (in my opinion) really suck because they never hit as hard and you dont get as nice of a speedy buzz no matter how much you take (compared to IR's), and they last SO long.
For me, the comedown also lasts twice as long as well, which creates big problems (ugh just thinking about it makes me cringe)
I take around 60-65 mg of IR's every other day and never really have 2 bad of a comedown and can always sleep (could never do this with XR's) , but I usually always have something to help with the comedown when they wear off.
Benzos work the best theres no doubt about that (combined with weed it becomes incredible), but for me when I dont have benzos (like today) I have some alcohol and weed and it makes me feel fine. Some people report not liking alcohol for the comedown but it does wonders for me and a friend.
Good luck and 120 mg is a high amount for anyone to be taking. The comedown must suck, trust me ive been there. As Someone who's done tons of adderall may I suggest not going over 60-65mgs, thats my golden rule and it works for me.
You live and you learn dont worry ive done my fair share of stupid shit with amps.