You really should see a doctor if you're having difficulty sitting and standing.
It's possible that you may not be getting all of your vitamins. A lot of vegans have difficulty getting certain vitamins and that can cause serious health complications.
i eat a bowl of kelloges in morning and evening and one meal of lunch...takes honey and lime juice in evening,,,,m honey at night,,, then also not losing weight,,,iam 33 years old my weight is 70 kg , iam 5ft 2 inch....m these days feeling tough to sit and stand as iam a teacher very difficult to work
As far as vegetarian diets go, do you eat eggs or cheese or completely sustain from all animal products? Both, although great sources of protein, can be very high in fat. So maybe use only egg whites in baking and limit your cheese to low fat varieties. You may want to also think about what kind of oils you use and op for canola oil or olive oil. Also coconut milk/meat, nuts, and avocado are all pretty high in fats. That doesn't mean you should avoid them, but I suggest counting how many grams of fat you're having. You want to aim for fat accounting for only 20% of your caloric intake. Meaning, 20% of your calories are from fats.
I would look into beans, lentils and tofu options. They're great sources of protein and usually lower in fat (and usually cheaper). Also try to eat 5-6 times a day, adding in the low fat/calorie snacks in between meals, keep your leafy green vegetables high, and your water at about 2 liters a day.