I'm not on Dianette (I'm on Cilest) but I have experienced similar side effects. Terrible mood swings for most of my cycle, becoming very emotional. I've also put on weight as I feel like eating more. I am thinking of just stopping taking the pill at all but as I use it to help my period and as a form of contraception, I really don't want to.
I suggest you go to the doctors. They do seem like typical side effects of the pill, however they might not be. Your doctor can advice you. He/she will probably get you to swap brands & if that doesn't work, suggest another form of contraception.