Sometimes I have EA/MCCC sex interactions (aka woohoo and try for baby) disabled (you can do that in WW under sex settings), other times I leave them on so I'll know when my sims wish to have a baby (I only try for baby/have sex without contraception when both sims want to have a baby). I ignore the MCCC birth control option (it only pops up when sims are flirty anyway, so it's not a problem, you should be able to disable it somewhere in the 'MCCC woohooer settings) and only use WW birth control. All you need to do is keep those two apart. MCCC birth control won't prevent WW sex pregnancy, WW birth control won't prevent try for baby pregnancy. You should use either EA/MCCC woohoo/try for baby/birth control options or WW sex/birth control options.
