Couldn’t get it fully in

I’m 19 male. My girlfriend(18F) and I tried having sex last night (both virgins) but I could only get the tip of my penis inside her.
She said it felt uncomfortable and like she was going to tear if anymore of my penis went in. She did make it clear that it wasn’t actually painful, just a bit uncomfortable.

We did foreplay for probably 30ish minutes (and we’d been teasing each other pretty much all day), she was wet and she said she felt ready. But we didn’t use any bought lube, maybe we should have?
I had a condom on and ik they have lube on them. We only tried missionary.

Any advice? All suggestions welcome