First of all, lots of guys go through this. Guys don't really talk about "not being able to get it up," but it happens all the time.
You're going through a pretty stressful time right now, even though it's probably fun too. It's common to experience a "dry spell" if you're in a new relationship, and especially if you've never had sex before. The stress can be powerful enough that you won't be able to jack off either.
This is totally normal.
My advice for now is to relax; this will go away. Be sure to stay clear of things that can inhibit your ability to get hard: alcohol, marijuana, cigarettes. All three of them can interfere with getting or maintaining an erection.
Certain prescription medications can also get in the way, so that can be a problem too.
Let's give this a couple of weeks and see if it gets easier.