Natural Plateau?

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I started working out and trying to lose weight 5 years ago. It took about 2 years to drop about 80 lbs and another year to drop another 10-20. Kind of hard to tell because I've been at or around the same 20-pound fluctuation for the past several years with very minor loses. I've tried all sorts of plateau breakers, but I typically end up frustrated and burn out. Even when I'm burned out, I still work out 3-4 times a week - I just don't count calories as closely. Last year was supposed to be my year and there is no possible way I could have worked out or dieted any more diligently, but I saw very little loss (I kept this up for about 6-7 months). I had my thyroid checked. It was reporting normal amounts. I even went off the pill. The doctor suggested maybe I was just at my natural plateau. I feel like I have enough extra weight on me that there is no way this should be my healthy size, but I have been obese pretty much my whole life. I'm basically at my smallest. I think I've only ever been about 10 lbs smaller and that was then I was working out way too much.

So I'm trying to recommit myself to this and use MFP as a guideline to reaching my goals, but confess I don't have the best attitude. Are there any tips for breaking through this stupid plateau I've been stuck on?

And because this will likely come up, I do switch up my workouts quite a bit. I do a little yoga, little weight training (though I'd like to be better at this but lack the knowledge of what I should be doing), elliptical, jog, kickbox (my favorite) and dance pretty much every week. I don't feel entirely comfortable making my food log open to the world, but I'm not entirely sure it would matter since I'm basically just starting and this has been a thing for the past few years.