Hi linger!
Firstly, it really does take a professional to diagnose. We can't do it, and really, you shouldn't either. There's nothing wrong with wondering about it of course, but it sounds like it may have crossed the line into self-diagnosis ("So it took me awhile to for sure realize I had manic-depression." <italics mine>), but then you say ("I'm only guessing I'm bipolar...") so maybe not. BUT, I can't help but wonder if you have basically self-diagnosed that that is having a strong influence on questioning the competence of your T, you know? ("I haven't exactly ran through the streets naked or painted my apartment all blue in one night, but I am capable of such impulsivity (well, maybe not the naked part) so just because I haven't done some grand gesture she can mark down as "crazy" I don't think means I'm not bipolar. So anyway, I'm guessing she wasn't very good at her job?") It didn't sound like she didn't try to diagnose you. Three sessions might not be enough, as they really do need to get a good sense of what is going on and what has gone on in your past. We really can't know just how in depth her questions were or if these things were discussed at each appointment or only one. Maybe it was too quick a decision. And maybe she simply didn't come to the conclusion you may have already convinced yourself of. (Also, when you say, "I could use advice in how to find a good psychologist who would be willing to diagnose me,..."<parentheses mine>), is it because you want to find someone to agree with a conclusion you may have already come to? One of the things that any professional needs to ascertain is the extent to which symptoms impair functioning. And that enough criteria are met. To use myself as an example, I have symptoms that are part of other diagnoses than the ones I have. But I am not diagnosed with those things because they do not impair my functioning to a high enough level to warrant it. Does that make sense?

One doesn't have to be behaving "crazily" while in an appt. to be diagnosed. (I used to wonder this with my migraines... how do they know if they don't see it, you know?) Thing is, it's the discussing of symptoms that helps them determine what is going on. Not saying that people don't get dx'd, say in an acutely full-on manic state, because that happens too. But then we'd mostly likely be talking BP I. With BP II, it can be a long process, as less intense hypomania can sometimes be explained away. Or not. (Heheh, personally speaking again, mine can be really obvious. And not that I even consider this as an example, but I have painted rooms all night on a whim. Many times. And yup, even in intense blue...)

Sorry I don't have much advice in the how to find a good therapist. I've pretty well lucked out on that front. One was referred by a GP, and the current one was sheer luck after a very long search. If it's ok to ask, how did you research them? And how do you know they act like her? Can't really speak to any phone or online things, having never done that. I'm a skeptic, part of it being not really knowing who they are, but also I think face to face has great value.

Hope this post comes off as kindly, because it is very much written in that spirit. I'm not saying anything one way or the other. It's just some stuff to consider. I can only get so much of a feel for your situation, and maybe my understanding is off base.