Missed period(s) due to gastritis or pregnancy?

Patient: I’ve missed my period twice, but before I “missed” the first one i had gastritis and did have a little bleeding and it felt like my period. I haven’t had one recently and i don’t know if i am to count the other one as a period. I’m scared that I’m pregnant! I’ve taken two pregnancy tests that were positive but i did them right.

Symptoms: Stomach pains whenever I eat anything