I can't keep it up with a condom!! Please help?

Okay so I am a freshman in college and have tried to have sex on multiple occasions. Let me give you some background information first. I am uncircumcised and I cannot retract my foreskin because of a tight foreskin (I am currently working on finding that problem by stretching methods). So well when I lost my virginity, I put the condom on and it didn't work. Second time we tried i got inside of her but I didn't feel anything at all. Like nothing at all. I've been trying with this one girl right now and whenever we do it without a condom (just a couple pumps) and it feels amazing and I can keep it up like that. But she doesn't wanna do it without condoms (I understand). Today, I went in I'm her room and we made out I gave her oral and then she gave me oral while I il opened the condom and put it on. I was using the Trojan bare skins (before this i have used ecstasy, ultra charged and few more) but then I went inside of her and didnt feel anything. I didn't sven feel my penis slip out her vagina and then it went soft. So she just gave me oral to finish me off. Like Cmon. What should I do??