Keep up with the practice sessions. Get use to the drysuit first with your single tank set up that your use to using. Give that a year in deep waters. Then go onto the dbles after your comfortable with the drysuit. I don’t think the doubles are your problem. It just may be you getting use to the drysuit. If your diving drysuit then you should try a heavy rubber fin such as a turtle fin. You could also have to much air in your drysuit working its way up to your feet. Good Luck and have fun.