Everytime I kill a dragon, mirror is there, and when it burns, he absorbs all the magical juice.

If you're too lazy to do the quest, doing anything to get around the problem [which really shouldn't be one; I ended up with over 20 souls before I even considered going to Solstheim] would take equal work, which you already said you don't want to do.

Have you tried a fresh install?

I hate it when mirror steals my soul

I know right? Happened to me the other day...

I hear that magical juice is good for the soul.

Anyways, best and permanent solution is to complete the Dragonborn questline.

But you need souls to complete the questline right?

He didn't say he didn't have any, just that Miraak was stealing the soul of any dragon he killed now. He also said he was too lazy to finish the main quest, not that he couldn't finish the main quest.

Only three.

For me it wasn't really him stealing souls that was the problem. It was the fact that it sometimes takes him forever to appear and actually absorb the soul so here I am just jumping around a dragon corpse thinking it might be a soul glitch.

Take the horn of Jurgen Wotsits back to Ustengrav if you have done that quest.

Try going to shearpoint
Try fast traveling to Dawnstar a few times