SOS problem with virgins

So, my boyfriend and I have been dating for a 7 months now and we have been sexual. We are still virgins, and he tried to fingering me. However, when he went down there he can only put 3 cm of his index finger in it without hurting. I’ve never inserted anything up there no fingers no tampons. And at times I’m tense. What can I do to be fingered ? I was really wet so I consider that as lube.