Scared of cancer on tail of pancreas. dr thinks ulcer but h pylori negative and don't drink, smoke, or nething else also pregnant. my worry justified?

Unlikely: Based on your age and the fact that you are healthy enough to get pregnant, it is statistically very unlikely that you have pancreatic tail cancer. There are other non-cancer diagnoses that can cause similar symptoms. If there is a continued concern, talk to your doctor about whether a MRI of the abdomen would be safe for you and your baby.