I have bipolar. Or at least I seem to - nobody will give me a diagnosis (I suspect they have one, but won't give it to me for some odd reason, although I have had all sorts mentioned, it seems that bipolar is the one they are settling on). I think I have type 1 though.
The way I understand it (or at least ime) the reason anti ds don't work in bipolar is that they work too well, if that makes sense. They send you high, even more high than you would be normally on a high.
I don't think this is you (because I don't know you) but quite a lot of people seem to say they have bipolar when they seem to have a more straightforward depression that comes and goes. To me, for it to be bipolar, the highs have to be enough to negatively affect your life. although it would seem that this type two might be proving me wrong there.
I get mild highs, where I sleep less, spend more money, drink more, take risks, get a massive sex drive, inflated sense of my own importance and intelligence and so on - a pain, and destroys any chance I had of living a completely normal life, but managable, and bigger highs where I have hallucinations, can't stop pacing up and down, get full on delusions and am generally "lost" to real life. Mercifully those are very rare these days, and I have learned to recognise the warning signs. The highs are followed by lows where I kind of can't cope with life - I hide away, tend to stay in bed, only eat and drink if really encouraged and so on. The lows are easy compared to the highs though - people "get" depression, they don't have that scared look that people get when faced with mania.
My advice is to accept all the specialist help you can get. I am currently under a team called Early Intervention, although they have quite strict rules on who they will help. I'm sure there will be a team that does fit you though, and if you have anything more than a simple and temporary depression, a GP will struggle, just because they have so much to deal with. Early intervention have taken me from literally having no life to living an almost entirely normal life and being mostly in control.