I was just going to suggest Grumpy and Happy.
Most operators cannot afford to take out a group of less than 4 or 6 snorkelers. It is mainly a fact of the fuel being so costly.
Unfortunately if you want to enjoy a private excursion you may well have to pay the price.
Please do post info you manage to find an outfit to do this.
I hope you have a wonderful anniversary - Mata Chica will be perfect.