Depression and birth control

I haven't been able to use the pill as it counteracts my depression meds (anti-depressant and mood stabilizer), but I'm having sex regularly and need more reassurance that I won't get pregnant than condoms or withdrawal.

Anyone know of a birth control pill or method that won't interfere with my mental health or make me gain weight? I gained a lot of weight on previous meds and I worked very hard to lose it. It does play into my mental health situation, it's not an issue of vanity.

Any help would be great.