I cant go on vaca with my bf cause I have stomach problems and anxiety about pooping when hes there, im scared ill have a stomach ache. I'm only 19...

You can get over it. It may take some time and effort, but you can get over this. A trusted CBT therapist can teach you skills and coach you through symptom mgmt including IBS issues. Bathroom shyness is common but extreme limiting degrees can be reduced to reasonable levels step-by-step. Life will be better overall if you get on the right track now. You'll be well prepared for rewarding well deserved vacation fun!