First, don’t panic! It can sometimes take a few tries until full penetration is achieved, and that doesn’t mean you have vaginismus.
I do think trying to get dilators would be super helpful, maybe your boyfriend can order them for you?
If dilators aren’t an option, I would start with your fingers or asking your boyfriend to use his fingers to help penetrate the opening, and try to massage the muscles and stretch the entrance. Moving them side to side in an attempt to widen the entrance.
If you can use tampons and get in two fingers, I think the penis is not getting in because of it’s size.
You might still have a fully intact hymen, which might need to break, and that can also feel like a barrier, but for most young women, the penis can do that with first intercourse, but it can be painful.
I’d try again with your partner really using his fingers first to open you up before he tries to insert his penis.
Let us know if you try again and what happens.