Before I say anything, I want to clarify that I am extremely young, 18 to be exact. Me and my girlfriend are always teasing each other in public. Every opportunity we have to be alone in public, like for example, an empty hallway, we’ll both start messing around, and I actually get a very full and normal erection every single time we do this. But, whenever I try to actually have sex with my girlfriend, I have a hard time getting and keeping an erection. Why does this happen? do I have ED at such young age? A few important details I’d like to mention is that I used to watch a lot of porn when I was even younger and didn’t have a girlfriend, so I don’t know if that has anything to do with my problem? Another thing ive noticed is that, while putting on condoms, I lose my erection quickly, and the other thing is that it might be the wrong size? It never reaches the bottom and its hard to put on AND it squishes the tip of my penis and it doesn’t look normal, it looks TOO tight to the condom and doesn’t seem comfortable, and I’ve read online that a condom that’s too small can cut off blood flow. Should I use viagras at such a young age? I don’t want to keep dissappointing my girlfriend and making her think she’s the problem when she’s clearly not. Help?