Help with preventing burning pain

I (f19) have been in a relationship with my partner (nb19) for 5 years now and I’m really starting to get annoyed with my inability to have sex. We’ve tried about 5 times now over the last 2 years with very little progress (we’d try more often but scheduling is a pain). I’ve tried insertion on my own but it’s super uncomfortable and painful, and I only get very turned on when I’m with my partner. I thought it was a lubrication issue but no matter how wet I am and how much lube we use it’s no use. We do plenty of foreplay, I’ve orgasmed before we’ve tried PIV, and nothing “loosens” me up. They aren’t outrageously huge or anything so I feel like I should be able to handle it but no dice. It’s a horrible burning sensation anywhere past an inch or 2 inside. It’s not a hymen issue as I have been to the gyno and she said there was no problem there (although I couldn’t complete the exam because the pain was too excruciating for her to fully insert the speculum).

Also to note that I have the same pain regarding tampons. When inserting them I have to be completely laying down in the bathtub or else they won’t go in at all, and even then they slowly get squeezed out. I’ve been able to keep them in for 6 hours but the first time I sit down with one in I feel it “fall” down and can then feel it inside me the rest of the time. I’ve heard this means that the tampon is too small, but then when I remove it later the pain is bad and it feels dry despite looking soaked which supposedly means it’s actually too big? I know it’s initially inserted all the way because the applicator physically can’t go any further without completely making it impossible to use.

I’m not sure what other details I could add, but I’m starting to get seriously worried. My partner doesn’t pressure me at all for sex so that isn’t necessarily a must but of course I’d still like to do it. At the very least I’m concerned with the fact I can’t have pelvic exams in my current state, which isn’t going to be great when they start being required in a year. Any advice would be so greatly appreciated, Google hasn’t been helping at all!