I'm a 21 yo virgin and the few sexual encounters I have had that led up to sex, I was not able to get an erection. Initially I thought it was due to alcohol since I pretty much always need to get drunk to be able to pull, but it then occurred during sober occasions. I think it may also be due to eating a girl out (which I always tried to do before) which may have put me off. Ultimately though I think it is due to nerves. Is this normal? How long does this last?