Come on over to the thyroid thread and join us. You do need to eat differently for hypo - more protein, fewer carbs, limit soy to one serving per day and limit raw cabbage, cauliflower and broccoli to name a few. You can lose weight. I have. A trip to a nutritionist can benefit you immensley. She will help you work out a plan with the food you like so you can lose.
You didn't say what your levels are. but you can be "high normal" and still not feel good and need more meds. Convincing the doctor of that can be hard. Some people also need a combination of meds so they are replacing both T3 and T4. A great website for thyroid info is
www.thyroid.about.com