Me and my girlfriend had our first times last night and we used a condom. Then after I ejaculated in it I went to tha bathroom,cleaned myself and peed,after that she gave me a blowjob and I squeezed just a little bit of transparent precum. After that we had unprotected sex for a little with not that deep penetration and I did not get even close to orgasm. After that I put on another condom and we kept having sex for a little more and she gave me a blowjob until I came again in a paper towel. I washed myself again then peed and she gave me a bj after that and we had deeper unprotected sex. While we were doing so, I kept pulling out and checking for precum, and there wasn't any at all. I was not close to orgasm well while inside her and I really doubt there were unnoticed leaks while we were having sex. When I had the second condom on after the first ejaculation there wasn't anymore cum in it. But now that I think about everything we have done, I am starting to feel really paranoid. If it's worth mentioning, her period started 6 days before we had sex and lasted 3 days. Should I be worried? Are there realistically any chances she could get pregnant?
Yes there is a chance she can get pregnant.
You can not clean out your urethra fully. Any semen from your previous ejaculation, not precum but semen with sperm, can be "squeezed" out of your penis and into her vagina. It only takes ONE sperm.
You may not even notice it.
Always use protection ALL the time.
She might consider using an emergency contraceptive such as Plan B or the Ipill.