I'm sorry you are struggling with health issues.  You are making a wonderful choice to go vegan.  Keep in mind that a vegan diet is not a guarentee of better health.  There are many commercial vegan junk food products on the market.  It is best to stick with whole foods and really learn to cook or prepare them.  Get rid of the processed cereal, mayonnaise, soda pop, bread.  Focus on eating lots of fresh or frozen fruits and vegetables, dried or canned beans (buy only the pure bean, not cans of processed baked beans and so on), whole grains from the bulk or organic section like oats, millet, brown or wild rices, quinoa.  If you eat nuts or seeds, buy them raw and whole without added salt, sugar, and oils.  Get away from cooking with oils.  They are concentrated fats that are overly processed and stripped of minerals.  You are better off using whole food fats like nuts and seeds and homemade or store bought nut butters with only the nut/seed for the ingredient and no added oils or sugar.  For salad dressings, keep it simple and use fresh fruits and sprinkle a few seeds like sesame or sunflower on them for flavor and stay away from commercial dressings.  You can even blend your own dressings with something like an orange and tomato and spices.  These fruit/vegetable dressings go well over bean/grain/vegetable dishes too.  Make fruits and vegetables the main part of your meals, every meal.  They should cover at least 1/2 or more of your plate.  Leafy greens are invaluable sources of calcium (low oxylate ones like kale, broccoli, bok choy, collard greens), iron, protein, and numerous micronutrients and vitamins.  Include at least 3 cups a day of them.  I like to saute them with tempeh or white beans and cinammon and vegetable broth for breakfast, and add them to salads and smoothies.  Or just munch on them raw.  Collard leaves make great sandwich wraps for mashed/refried beans, hummus, nut butters, quinoa, etc.  

Foods such as sweet potatoes, winter squashes, bananas and so on make nice treats and are very filling and satisfying without being too calorie dense.  Just don't add too much stuff to them.  A few spices or a splash of pure cocoa powder or plant milk is good enough.

Stay away from sugar, white flour, concentrated oils.  Use fresh fruit/juices for sweeteners to go with whole grain hot cereals or salads or stir fries etc.  

When you get rid of the junk food, highly processed foods, extra salt and sugar, you begin to appreciate the natural tastes and textures of whole foods.  Your energy level and clarity and digestion will improve, trust me.  I have never even been close to overweight in my life but when I went vegan (three years ago this week) my energy level and stamina soared!  I ate healthy before then but getting dairy and meat out of my diet improved m y cholesterol numbers, digestion, got rid of sluggishness and sinus issues.  it is well worth it!  

And don't forget that getting enough sleep and exercising every day is also very important.  I exercise six days a week and have since 2008.  But even three or four days would be great.  Exercise is not only about weight loss but about reducing stress, gaining strength and stamina and energy, increasing metabolism.  Find something you will enjoy and stick with.  make sure to get your heart pumping and not just a casual walk.  You don't have to kill yourself with it, but intensity matters.  Building muscle with lifting weights or calisthenics is also a good idea.  Increased muscle means increased metabolism and burning calories at rest.  

Find a dietician who works with vegans or vegetarians or who is at least open to it.  Hope this helps!  Best wishes on your journey.  Try reading "Forks Over Knives" or "Eat to Live" by Joel Fuhrman.  Check out your local library or bookstore or browse Amazon.com for some vegan cookbooks and nutrition books to help you figure out some good recipes.  Lots of good stuff on Vegweb but be careful as a lot of it is junk food too.