^This post is seriously spot on. This wise man put it to you exactly how it is. If you're going to get into IV drug use you really gotto take it seriously and know your shit before you really even touch a needle. Practice with saline is also good.
But yeah dude our point is that nobody whos got iv'ing down pat is missing entire shots. Of course people slip out of the vein and stop injecting and register again, or they miss completely, pull out and then try again. But to miss the entire shot you have to literally pump the entire dose under your skin which is painful and like i said before super obvious that you're not in the vein at all. At this point you dont just hope for the best and keep pushing in. Unless you want to skinpop the shot, you pull out, and you attempt to register again, when you know what you're doing missing shots really is unacceptable.
Nothing wrong with intravenously using ketamine, given your tolerance, it's much safer for you than a ketamin naive person, as you said you havn't been losing reality before you got the needle out so no dramas there, just really take it seriously and learn to inject well. This inevitably takes time and if some ideally, abit of saline as well.
Once you get to the point where you can confidently and stressfreely put that needle into your vein and pump the solution in no worries and you can do this mostly everytime first time unless it's an unfamiliar or new site, you know you're good to go. Plus you will obviously know whether you've got it down or not.
Please dont take this post as condescending. I'm not at all putting you down for not being some injecting all-star. Just trying to help you be in a position where you can make your injecting as least damaging and easy as possible.
As others have stated do not underestimate the power of vitamin E creams for skin healing. And do not understimate how much exercise all every kind improves your vein accessability. Hydration is even more important.
Good luck dude, you can't know enough man. I recommend learning, learning some more, then relearning all of this. It will be worth it many times over man. Between me and you i quite like having this little skill mastered haha.
Okay in conclusion dude do not stress about your missed shot. It will become very obvious to you if it becomes infected, but the odds are it will just heal perfectly no harm done. It's not a bad thing or anything, the risk is purely that your shot didnt come from a medical ampule, and thus could have introduced foreign matter to the injection site, this aint a problem when its injected to a vein as it flows to your lungs and heart ect(still not healthy obviously), but of course if they a skinpopped, the site can become infected and an abcess form. I wouldn't knowingly put anything into my muscle that hasn't been through nothing less finer than a 0.20um micron filter for this reason.
To give you some peace of mind a month ago i was mindlessly mucking around, and some how managed to inject 20 units of "mother" the energy drink, under my skin. This was with a seriously old and barbed needle. I was just messing around and didnt even realise the bevel had puntured and entered my skin. When i pushed the plunger down mesing around i felt the familiar skin pop feeling and was DISGUSTED. Seriously. But you know what? I didn't get any infection and the solution didn't even irritate tissue or anything just absorbed and no infection resulted. So chances are you will be fine, but of course definitely possible you did introduce something.