stressed out possible father
That's a horrible situation to be in, I'm sorry. I'm not an expert but it sounds like you had sex just after her period? Maybe too close fo rher to be pregnant, but like i say, I'm not an expert.
I hope you find some answers in this but be prepared for not being able ot find out until after the baby is born.
If you have sex...there is a chance. Best thing you can do is prepare yourself in case you are the dad, do your best to handle your stress, start looking into what your rights are and preparing yourself "legally" and when the baby is born have a paternity test done asap. (maybe even try doing an estimate due date on your own and look into what you need to be doing to make sure a test gets done asap...don't wait until the child is a year old)
I'm also 10wks pregnant - my LMP was Nov 13th, I ovulated on the 27th. So similar to what your gf is describing, but I have 30 day cycles. My only concern for you is that if she ovulated on the 29th, and you DTD on the 22nd...well, those swimmers don't last 7 days. Your guys have 5 days tops, in prime conditions. I hate to do the math this way, but unless she ovulated much earlier than you think (like the 24th or 25th), chances are not in your favor. I'd say the odds could go either way - 50/50. Definitely get a paternity test.
So sorry you have to be in this position...it's got to be so difficult. Best of luck to you, and I wish you much peace with whatever happens.
I don't know what the laws are in your state, but an unmarried father definitely can have an uphill battle to get and maintain paternal and custody rights (even shared).