When it comes to weight loss, what matters most is what we eat. Good nutrition is what takes the weight off and keeps it off. Exercise is what keeps our bodies fit and healthy. A person CAN lose weight without exercise. However, most experts will tell you that overall good health is a combination of good diet and some regular exercise. Because of your injury, exercise will be difficult, but not impossible.
Ideally, a person with extensive knee issues really should talk to their doctor to find out what exercises they should and shouldn't do. Since you don't have medical insurance, that's going to be difficult.
One thing you could do (and please take my advice with a grain of salt since I am not a doctor) are chair exercises. If you find it difficult to stand for long periods because of your knees, then sit in a chair and do some upper body strength exercises with either hand weights or resistance bands. Coach Nicole also has a short 10-15 minute chair aerobics routine you "might" try. If you find a particular exercise she does bothers your knee while sitting, then stop doing that exercise. www.sparkpeople.com/resource/videos-detail
Upper body strength or even core exercises are possible exercises you could do that (in theory) shouldn't hurt your knees. But once again, listen to your body. Don't do anything that causes you pain.
Getting back to nutrition for a moment. yes, a vegetarian CAN gain weight ! How ? as the PP noted, if they eat too much of everything, they'll gain weight. French fries do qualify as vegetarian. So, if a vegetarian were to eat French Fries at every meal, at some point, they would gain weight if they are sedentary.
Now, I hope you don't mind, but I took a quick look at your food diary. I'm not criticizing, but if you want to start losing weight, the Mountain Dew has to go. Regular Mountain Dew has over 200+ calories per can. If you drink two cans, that's 400+ calories. plus, it's loaded with an insane amount of sugar. Many studies have shown that when our blood sugar spikes (after drinking soda) and then crashes after that energy rush, a person craves more food or soda. that's because our bodies are looking for that next rush.
If you want to lose weight, try eliminating the regular soda. If you'd really like soda, then swap to the diet version of mountain dew. that will save you over 400 calories a day if you drink two cans or more per day. Just making that one change could help you lose a pound a week depending on how much you drink. A person shouldn't be drinking their daily calories. If your food diary is correct, at least 25% of your caloric intake comes from soda.
Also, watch the cheese. I love cheese as much as the next person, but... calories in cheese adds up fast if you're not mindful of the portion. Do you log the veggies you eat ? Looking through your food diary, I don't see a whole lot of fruits or veggies logged. If you really want to lose weight, do your best to eat 6-9 servings of fresh fruit and veggies each and every day.
If I were to go back in time and give myself one piece of advice that would help me lose weight, it would be to increase the amount of veggies I ate.
Just a few random thoughts.