Is it just stress, or what? I'm really struggling...

Lately, life just feels heavy. There are days when I honestly struggle to find any motivation. It’s not like my life is a disaster—my parents are awesome and super supportive, and I actually just started a new job three weeks ago... I'm 19.
I've got a couple of things weighing on me. First off, I had my first sexual experience with a girl, and it didn't exactly go smoothly. Like, during all the touching and everything, I had an erection, but once it was time to actually get down to business, it just vanished. I don't know, maybe I was just too stressed out or something... The second time went better, I had one, but it didn't last very long... it was more like a "halfway" encounter. My question is, why did this happen? Now I'm just terrified it'll happen again next time.
The second thing has been bothering me for a while now and I really can't figure out what's wrong... Basically, whenever I need to pee and there's someone nearby, I just can't do it. I don't care if it's friends or a complete stranger, I just freeze up. Because of that, I often have to leave bars or clubs just to find a spot to go... If the restroom is crowded, I'm stuck. The only time it's fine is if I've had a few drinks, 🙂 then I don't have any issues at all. These things really mess with my head and I have no clue what the root cause is.
PLEASE, can anyone help me out and try to explain why this is happening???
I don't smoke, and I only drink on weekends when I'm hanging out with my crew. I'm pretty outgoing, I'm not shy about anything, and I can talk to just about anyone... I'm definitely not a closed-off person.

Honestly, I get it—writing something like this in front of someone else feels pretty awkward. It’s not the end of the world, though. Personally, I think serving in the military would probably shake off most of that shyness for you...
Look, if you're struggling to talk to a girl, it basically means you're lacking a bit of self-confidence and guts right now. But hey, that's totally normal—you're young. Things will settle down eventually. Just take it easy; you're only 19, and you've got plenty of time ahead of you. Maybe go chat with your family doctor about it—see what their take is...

Your problem is that you’re overthinking this constantly, so when the moment actually arrives, you freeze up. You need to chill out and stop obsessing over sex; just let things happen naturally. Look at those couples who are desperate to have kids—they try everything under the sun, but nothing works. They're perfectly healthy. It’s only when they stop forcing it that they finally conceive. Take my word for it!

I used to get those same nerves—feeling like everyone was watching and judging—but once I realized that I’m doing fine and that some random stranger's opinion doesn't actually carry any weight, everything changed. Like dustyowl29 said, you're still young—things have a way of settling into place eventually.

John M. said:maybe talk to your primary care doctor about this and see what they think..

A primary care doctor???

I doubt they can really help with this. Someone made a good point earlier that it’s likely just a lack of self-confidence, probably because he hasn't gained enough experience yet—and I'm guessing all his friends are having regular sex...

Just try to relax, learn to love yourself, and build some self-respect. If that doesn't work, I'd suggest talking to a therapist...