The vamp regen doesnt seem to work with fists/gloves.
Also neg burst doesn't apply any strength taken
Where you using neg burst as a cast spell at the level required to gain the strength drain part of the perk or as an item? As an item/scroll/wand it will not apply the strength bonus. They also need to fail the saving throw to drain it from them too mind you.
Was using the spell and they failed, I believe the problem is it doesnt stack on top of any strength buff you already have since when I was dispelled it did say neg burst ontop of it removed.