If he is inserting his penis (even partially) into your vagina, then it is sex. I think that your uncertainty means that you and your bf should make sure that you are well educated on the subject before you continue to put yourself in this situation. Sex is a big deal and you each are equally responible for any consequences that could come of it. Just make sure that YOU know exactly what is going on and that you aren’t relying on someone else for your information, ok Sweetie? You can definitely ask me any more questions you may have.