Hi newmember! I’m so sorry to hear about the pain you had in your first sexual experience; it definitely does sound possible that you could have vaginismus and that dilating would help, as Melissa says.
One thing I will say is that vaginismus and sexual pain issues are made worse by anxiety, and it sounds like you have a fair amount of distress surrounding sex as well (for example, your worry that you’ll become pregnant). Are you on birth control or using protection like condoms when you attempt sex? It might be a source of reassurance, as could be working with dilators to get more comfortable with penetration. I think it’s great that you’re seeking help and looking for answers and I hope some of what we’ve said will help you feel more comfortable!