Ok. Take a deep breath. Right now, your main concern is finding a resort...try not to think of ANYTHING ELSE right now.
I'd say talk to a TA, this forum has a some great ones.
I'm getting married in Cancun/Riveria Maya so I am a bit biased to my resort....Moon Palace. It's AI, kid friendly, has 3 gazeebo's for weddings as well as terrace set ups and as for affordiablitly, our guests are spending $422 per night and if they stay 3 or more nights, it includes excursions.
One thing and one day at a time!