It takes time really. Men are going to go faster without a condom because there is more friction for him. That's just how it is. You can either keep trying or go back to condoms. One way to delay his o is when he feels like he is close to just stop moving (both of you) and usually that will help prolong the experience. Remember, birth control pills are not 100% effective anyway, especially if you do not take them at the same time everyday or if you forget to take pills.