Birth control might leave your system faster than you think. I got pregnant the first month off the pill when we tried for Brady (miscarried the first pregnancy, pregnant again the next month - so technically, I got pregnant twice within 3 months of being off pills), then with Makenna, I got pregnant in the 2nd month of being off pills.
I had been on a cocktail of birth control from age 15 to age 26.
But... I also tracked my body's signals and nailed it just right each time. I tried to take the relaxed route and just "let it happen" with Makenna and quickly gave that up after I got my first period after the first month of trying... said screw that and got all analytical on it! lol