Why don't I peel any more from chemical peels? The first 2 worked great! What's going on? My goal is to lighten my melasma.

I got a Jessner's Peel in Oct & Nov. My ENTIRE face peeled like CRAZY both times. I got the Vi peel in Dec. I peeled around mouth but that's it. I got the Jessner's in March. I didn't peel at all. I know they say just because skin doesn't peel that doesn't mean there isn't improvement. However, I only had improvement with my first 2 peels when I peeled like crazy. The Vi peel made my skin look worse actually, and the last Jessner's didn't improve my melasma like the first 2 did.