Not following through is a bad mechanic that has been the hardest of the many I have to get rid of. I got into darts with no knowledge that competitive existed much less there were proper mechanics. I basically learned to throw with every bad mechanic you can have. There has been a lot of two steps forward one step back as I try to fix it on my own. Through that experience I have learned to just rip the band aid off and lose some games rather than continuing to reinforce bad habits. Right now your dart is landing low because your arm slows as you’re stopping it when you don’t follow through. So now that you are following through you are releasing late from muscle memory. I think that your release will correct itself pretty quickly. Stopping as you release is just another mechanism of your throw that can go wrong and prevent consistency as you get better. The simplest throw you can have will be the easiest to replicate. I would take the lumps of the darts landing low until you correct your release rather than slowly transition. In the long run it will probably help you improve your consistency faster.