I’m not on the right path as a young women... Advice would help

I just got out of a 4 year relationship. We had a son but he died during labor and this was 8 months ago. We’ve been separated for 3 months and I actually have a new boyfriend. It’s been 3 weeks.... I’m in med school I’m trying to focus on me. He didn’t pull out last night and I’m freaking out and he’s so calm about it and I’m shitting my pants. I do not want to get pregnant yet nor have been with him for long. I need a reality check. Please