Personally, I think therapy is best done in person, or at least started that way. I just think it's much harder to get a sense of a therapist, and they for you, online, and a lot can get missed. I also think it's just easier to get a good vibe check in a shared physical space, you know?
A sex therapist and an OBGYN are different people. OBGYNS actually often aren't particularly educated about sex, because that's only a very tiny part of their education. Obstetrics -- the business of pregnancy and birth -- is actually the biggest part of that training, and gynecology -- which is about the whole of the reproductive system -- usually comes second. But neither of those things are about sex and sexuality, which is not largely about body parts at all, and when it is, it's as much about the central nervous system and your brain as it is about your genitals.
"Sexual dysfunction" is a tricky term, and one I'd generally suggest people figure is a bit of a red flag when people use it, because, to me, that can show that people may not realize or support that human sexuality and sexual function are diverse, not something where there is a"right" way for things to be working. (I also find it ableist, by that token.) For instance, I would not call someone who, for example, can't get an erection someone suffering from sexual dysfunction, because we don't need an erect penis or clitoris to be sexual people experiencing or exploring our sexuality. I also would not classify what's been going on with you as dysfunctional, period: I still think that vaginismus aside, what's mostly going on here is that you just haven't found your groove yet, and all this hyperfocus on orgasm and making things work has probably really gotten in the way of that. It's not uncommon for young people to still be at the start of figuring out what feels good for them sexually, alone or with partners. That's the most normal thing in the world, truly. I suspect that sexual media has given a lot of younger people the idea that sexual response or sexual pleasure is something that comes instant and easy, when that's not usually the case (heck, it's not even the case IN sexual media as it's being made, editing just does a loooottt of lifting to make it look effortless).
That said, yes, you can screen OBGYNs when it comes to which of them are more proficient and educated about sex and sexuality, and some will make that a part of their practice. You can ask questions of a provider like, "How much focus do you have on sex and sexuality in your practice?" or "How much experience do you have working with people with vaginismus?" to screen for the kinds of help you need. I'd be happy to make up a little list of screening questions I think would be helpful for you in seeking out a new OBGYN, if you'd like.
Per the sex therapist, since you're in the United States, I'd say there are a couple good options.
Psychology Today has a huge therapist database that you can use filters on to pick things like the area someone works in, their age, who they serve, and what kinds of therapy they provide, including sex therapy:
https://www.psychologytoday.com/us/ther ... ex-therapy
AASECT, which is a professional support organization for sex therapists and other sexuality professionals also has a reliable database here:
https://www.aasect.org/referral-directory