If you aren't happy you can certainly try your best to work on things. Arguing isn't working on things, just to clarify. You have to want to turn this into a positive thing instead of the blame game, you need to do more of this, etc. etc. Don't raise your voice, don't get into stupid arguments over petty things, and just take a step back and really look at everything. You might even need some time on your own to really get shit in order, but do not do that unless it's very clear that she doesn't want to continue to work on things. It really takes two to fix this and that's if it's not beyond repair at this point already.
Start with identifying problems, and not just on her end, things you are donig wrong too. I think you have a suspicion on what you are doing wrong as well.
And yeah, you are definately not ready for a kid. I do not anything about you but the couple paragraphs you wrote above, but if you can't figure out what to do and how to handle this situation, I can't imagine you are ready to raise a kid. You ever watch that show Teen Mom? Does that look glamorous to you? Be thankful that she ended up with a late period (which could be from stress ya know!).
Waking up next to a beautiful girl,
Step outside and say hello to my beautiful world.