You do 100 crunches a day, but your abs are still not rock hard like you want for bikini season. If carrying around some extra weight around your middle isn't the problem, then another issue may be that you're resting between reps.
To get strong, sculpted ab muscles, when doing crunches, don't let the back of your head or shoulder blades touch the floor between reps. In order to tone your waist, the muscles must be fully engaged, and as soon as you release your body to the floor, you lose that tension. If you can't resist the urge to take a little snooze on the floor between reps, try doing your crunches on a stability ball. Since your upper body is floating in space, so you're forced to keep your abs engaged.