Another thumbsucker...

I already have 2 thumbsuckers, one of them is 5 and the other is almost 3, and they STILL suck their thumbs. I SWORE I would do all I could to not have another thumbsucker, we put in the binky everytime we see Ryan sucking his fist, but the other day I found he had fallen asleep with his thumb in his mouth. What am I going to do with another one!!!