I'm glad that you posted, but I'm sorry to hear that things have been rough lately. I think that els made some really important points; notably with the doctor and your new special friend.
I really don't know a lot about meds, only from my own experience, but it sounds like the doctor is making a lot of changes very quickly. Most of that stuff takes several weeks to reach effectivness so there may be a better way of changing the medication that would let you get to the theraputic level without feeling so crummy in the interim so you could at least have a chance to evaluate them properly. Otherwise, you may be discontinuing a med program that could be beneficial. Too, if its on a 4 weekly (ie. monthly) type of schedule, there may some sort of female hormone interaction making it worse. I never had pms until I started the meds and didn't realize that's what it was until I was in the doctors office bawling about it. The important part for me was to realize that I can manage the pms and exercise and help to keep myself relaxed and it will usually subside. Otherwise, when I forget, I'm a total mess for days since I feel like I'm getting sick again.
Although it sounds like your dr is trying to help, it doesn't sound like he's really hearing your concerns. It may be time to look for a second opinion, preferrably one who understands that weight gain is a big upset to a person, particularly to an 18 year old woman. I too have suffered through the weight gain with the depakote. I'm lucky that I'm not 18 and don't feel as much pressure - it took me a while to come to terms with the new me, but for now I've been holding steady with the weight and been pretty stable. I don't think that its simply a matter of diet and exercise. The meds don't help at all, especially when you're not feeling well enough to eat properly or exercise well in the first place. I think that nrs2b posted some really good links on womens mental health that had some super information on clinics and programs that cater to women. There may be a link on those sites that could connect you with a dr. in your area who works the same way.
And the relationship thing - I've thought lots about that too. The big part, like els said - everybody has something to deal with. I know that for us, we feel a great deal of guilt and upset for putting this up for people to deal with. The part that I try to remember, is that as a whole, people with BP are very sensitive, caring, charismatic, giving people and that is the gift we can offer over lots of people who might be more "average". I've been lucky and have been open about BP with the people that I date, relatively early on. Since I was diagnosed first with depression, then with BP, I wanted to make it a non-issue. For me, if I think that they're worth the effort of a friendship, or relationship, I've been open to letting them know that I'm a little different and explain that sometimes I need to take extra care of myself. It doesn't mean that I'm damaged goods, just that this is my cross to bear. I too am of the mind that if they can't deal with this, then that's ok too, but I need people in my life who are supportive. Even if you or this fellow, aren't up for the challenge of BP in a relationship, he would probably appreciate the chance to understand where you're coming from if you choose to completely end the relationship based on this one point. Maybe there will be a point later on, when you're more stable that you guys might want to hang out again.
Please take care of yourself and know that you're in my thoughts,