I'm not sure why you are eliminating meat, but not other animals, like fish.
Personally, I have not eaten dead animals for over 35 years, and feel much better for it; for me, it is largely an ethical issue. There are, of course, health issues, as well. For years, my brother has made fun of my vegetarianism; I refrain from commenting on his open heart surgery, stent insertion, etc. I prefer my way.

I have been fairly overweight for years, and have recently dropped 50 lbs by eliminating all gluten from my diet. I recently learned about my gluten intolerance, and the damage it has done to my body, including the destruction of my peripheral nerves. While I'll be the first to say that It is damned inconvenient to be a gluten-free vegetarian, I am convinced that it's right for me. It does take a lot of effort in food preparation, as well as research for proper nutrition. I do consume dairy, and take a great deal of B12, glutathione, etc.

The weight gain you mentioned may be caused by many things, including medication. Be careful about consuming too much fructose; a diet high in fruit may not work for you.

Good luck in your quest.