Hi there, Ssoph_1! We can do guidance <3
Sex being a new activity for you could be contributing to the tenseness and pain you've noticed. That wouldn't rule out vaginismus, though, because it is partly psychological. We have a resource about the condition, if you'd like to have it on hand:
The FBI Files: Vaginismus
I understand how the idea that you could have a condition like vaginismus would be scary, and how it would feel disappointing to consider that you won't be able to do any of the things you want with your partner. So, I hope it will be good news that I think your fears are unfounded. If this is vaginismus, it wouldn't be a sentence to a life without pleasurable partnered sex. This is a manageable condition. While you have it, it might make insertive sex a little difficult, but there are plenty of other ways to explore sexual pleasure and intimacy with your boyfriend. PIV sex is just one activity-- it does not have to be the focus of the sex you have.
To be clear, this isn't to say that you should expect never to have insertive sex. It is very likely that you will be able to do it, at some point. I just want to caution against pressuring yourself to do activities that are not working for you right now, based on the pain you've noticed.
How does that sound, to you?
P.S. I was thinking, and I'd like to share one of my favorite articles of ours here, because it describes a way of thinking about the things we can and cannot do during sex that I think is really helpful. Would you read it, and tell us what you think?:
Disability Dharma: What Including & Learning From Disability Can Teach (Everyone) About Sex