Undiagnosed but pretty sure

So I'm 20, and have had plenty of sex (good for me), but occasionally and recently every time, it's so tight down there and impossible to penetrate! Lubrication is NOT an issue, and neither is arousal. I have a GP appointment September 1st, because I'm switching from the pill to the injections (I can't have the implant). I guess I'm just wondering how other people cope, I'm considering requesting animation-depressants, because my anxiety and depression are being made so much worse by the problem!