I am a vegetarian, so can't have meat in my diet. Is there any alternate to increase BMI? And how to differ better between excessive belly fat & bloat

Yes. increase amonut of carbs in diet like potato sweet potato grains like wheat corn oatmeal rice etc. increase nuts and cold-pressed oils. Cold pressed oils are made by just squeezing the seed and are not hydrogenated. One such company is haine that makes cold pressed oils. Best of luck. Get proteins from beans soy and dairy products.