I've been on the pill & recently switched to the shots, depo provera. I've lost weight on both with no real problems. Weight gain is only a possibilty, not a given. If you continue to stick with this WOE, you should be OK. It might slow you down a little, but it won't prevent you from losing. Getting pregnant on the other hand...I think you know where I'm going with this. If you discover the pill is problematic for you, you can always stop taking it & use another method. Might as well give it a try for a couple months & see how it affects you & your body.
God Bless,
Amy-Lynne