Hi Alwyz!
What you're going through is really scary, but you're not alone! Hopefully, all your tests will come back negative.
I was diagnosed with breast cancer when I was 25. I'm 27 now and in full remission

If you don't mind, pls post your test results -- I'll be thinking about you.
The only adivce I can offer at this point is to try not to think about it too much, b/c worrying doesn't make test results come back faster. The other important thing that I think many people overlook is that cancer is NOT a death sentence. Say your tests come back positive...well, you'll have to go through lots of treatment, and you may feel like setting up a cot in the hospital, but most likely, you'll be fine!
One last thing...it sounds like your Dr is on top of things, but in the event that you ever hear the words "You're too young to have cancer" find a new Dr.
I'll be thinking of you!