I was on my 3rd day of my period and I had unprotected sex could I get pregnant? Should I take to plan be pill but it already been 3 days now

Yes, you could have gotten pregnant. Any time a penis is inserted into a vagina pregnancy is a possibility.

It's too late to take Plan B. You will have to wait to see if your period comes next month as expected.

Agreed, of course you can get pregnant, while the chances are less, there is a chance. Happens all the time.

No it is too late to take anything now, you will have to just wait and see