Need help.. PIED or Performance anxiety??? What do i do ?

I'm 20 and I've been watching porn since I was probably 13 and for the past year been trying to slow down but haven't watched porn in about 2 weeks because I'm trying to stop completely. I've had sex with a lot of females and every time I do it's hard for me to get my dick up sometimes more than others. I justrecently started seeing this girl that Ireally like and tried to have sex but my dick went completely limp right before I was about to put it in. I had no problem getting hard while making out though. I felt so bad and imbaressed that I tried to blame it on her . This would also happenwith the last girl I was having sex with but sometimes we would have good sex and I would even cum(I was watching porn more often then) It scares me because I don't know when it will happen or won'tand I'm trying to keep this girl but don'twant to bring this situation up with her . I need some advice would VlAGRA help or even those pills they sell at the liquorstore ? I feel hopeless at this moment