I was 5'8", 130 lbs before pregnancy, first I lost 10 lbs, and I am now 131 lbs at 21 weeks.
I don't really know, but I think it might be a little bit of weight gain, but talk to your doc, he'll know more... On the other hand you are supposed to gain some weight during pregnancy, so I don't think that's a problem. As long as it's not too much.
About going to the bathroom: I have to go every 15 - 30 min since 12 weeks, I guess that's normal...