I've been pregnant on my period before. when this happens, could you still get a positive test? the 1st month i had a period and i missed the 2nd mont

Yes: If you are pregnant, the test will be positive. And you were not pregnant when on your period. Implantation can be as heavy as a period and fall at the time you would expect it, but it is not a period.

Yes: The chemical that gives you the positive test is produced by the placenta and as long as there is a normal pregnancy the test should still be positive. Some times an "implantation " bleed can mimic a period.