Question RE Dart Stance/Weight Distribution

The angled dart stance seems natural to me, however I feel my left foot (balance ft) coming off of the floor when I pull the dart from my offhand (left) hand. I gather that from not having a stable/solid stance this prevents weight distribution.

Any suggestions on how to keep the left (balance) foot planted to the floor so the weight can be distributed 75% to right foot(support) + 25% to balance foot?

Thanks