This should sound more generic than only for a safety stop during a dive.
I had this issue that during the swim as well, that I had to constantly fight to keep from rolling to one side, or to keep my feet from floating towards the surface.
The two most typical problems with swimmers/divers that I saw were :
The feet looked to have a tendency to move towards the bottom while their upper body moves toward the surface, meaning, that the center of gravity would be so low on the body that, some of the weight needs to be re-positioned towards the shoulders.
Or the other way round: such that the feet kinda had a tendency to float towards the surface.
The second is your case I guess. You need more weight closer to the lower half of your body in order to balance the center of gravity. Should you be using ankle weights? 2 lb may be?
One quick notes: If you are in wet suit, and if you think that you are concerned that there is air in your booties,ensure the boots are outside (are not tucked inside) the wet suit leg.
Also, rather than investing in ankle weights right away, before you do so, try a dive with very little gas inside your suit. And, Use your BC to maintain neutral buoyancy. Actually you can practice diving with a minimum of gas inside your dry-suit, It may cause the floaty-feet problem to be solved.
Or another quick solution to try can be: A pair of Aqualung jet fins. I have heard a friend who had resolved the issue with that. But I personally believe more in classic-style to resolve such an issue rather than finding a work-around solution.
P.S.: The re-positioning of the weight should be such that you don't also start experiencing the first problem noted above.