My mare isn't producing milk, and she has a 3 month old colt by her side. He sucked her down quite a bit, but she's on a fat supplement and a 14% mare/foal feed along with free choice brome. I upped her feed a bit, but noticed this week that her bag was getting smaller. Today it was basically almost normal size, and no milk when I squeezed. Am I able to safely wean the colt early? Suggestions for that?

I have weaned several at 3 months over the years for various reasons. Make sure the foal is eating and drinking well before separating them. If the mare has no milk the foal is effectively weaned from her as a nutitional source so I would either add milk replacement pellets to the foals feed or see if it wants milk still from a bucket using milk replacer. My 3 month old is nursing some still but he is eating hay and some of mommas feed ration and drinking water, so if I had to separate now I could. Some foals learn about food early, some take a while. 

Is your baby eating grain & hay really well? That is a must before you wean. If so get a good foal feed to start him on & make sure he is eating it before  you wean. We have always had really good luck with Omolene 300 and is now has Outlast in it which is a Gastric Support Supplement. ( everyone has their favorite foal feed )

Be sure he is drinking water but not to much. Too much water can cause scours.

Do you have other foals ??? Companionship is huge also.

I would increase concentrate feed to the mare.  More feed is uaually the solution.  

I upped her feed quite a bit, and added a fat supplement. She's starting to gain now. The colt doesn't seem to really be nursing, her bag is gone and he's eating/drinking just fine. I decided to just keep him with the mare until mid october when I was planning on weaning him anyways.