On the second day of my period, i had a tampon inside and i was in a lake with my boyfriend. he rubbed penis against vagina for 30 seconds, he never ejaculated. am i pregnant? this was also all underwater.

Do you have: a positive pregnancy test? That is the only way to know if you are pregnant. It is very unlikely given the circumstances you have given. Ovulation usually doesn't occur during your period. A tampon isn't a contraceptive device however. Ejaculation isn't necessary for sperm to exit the penis and if the penis is in contact with the vagina water doesn't matter. If you miss a period take a test.