[painful sex] how do you know if you're sufficiently aroused?

Hi Reddit,

I'm going to see a doctor about this, but I won't to hear your opinions to help me push back on it being told it's all in my head if i need to.

Female, 20s. I've been sexually active for about a year - same partner, LDR so we only see each other every two months or so. Penetrative sex for me has almost always hurt and even when it doesn't hurt (just one or two times) it doesn't feel pleasurable? Sometimes it burns on initial insertion but if we go slow it stops hurting after a while. Sometimes if it's a little uncomfortable when we first put it in then if we take it out and put it back in the second try hurts like hellfire - like burning pain and we have to stop. This happens whether I'm on top or on bottom. It seems easiest if I'm on top with BF in a sitting position too but even then no guarantees.

Usually BF makes sure I have an orgasm first - so I always thought I was aroused enough. We use lube, but it can be tough to get it into my vagina and on all sides inside. But even if I'm dripping wet before penetration it can still be painful. How aroused do I need to be?

It could be vaginismus i guess but I can use tampons without a problem and also once he's inserted it usually hurts less and then it's thrusting that makes it hurt more. Which makes it sound like a lube issue. But how much lube do we need?

Lost here, Reddit. Please help!

TLDR: penetration hurts sometimes, burning sensation even if I've already had an orgasm and am dripping wet. How much arousal/lube do I need to rule out vaginismus?