How do you "eat enough"?

280tofit2014

I admit, after joining MFP I've lost 30lbs quicker then I ever have before and I have never been so motivated to keep on but since I've been logging my food and doing portion sizes I can't seem to "eat enough"? I have meals that to me feel like a lot but end up calculating from 700-1100 for the day. MFP had me set at 1300 then after I lost 30 I adjusted and it has me at 1800. I cannot for the life of me reach that. My fear is plateauing. I know it'll happen eventually because that's part of losing weight but I don't want to unintentionally cause it to happen faster. I exercise 6 days a week for 2 hours at a time. My HRM says I burn anywhere between 500-1000 calories, depends on what I'm doing. How accurate is MFP calories suggestion? Any food recommendations? I have cut out dairy, sodas, fast food, etc. trying to cut out carbs. I'm not a high meat eater and have been allergic to the last 3 protein powders I've tried I cannot do chocolate or vanilla flavoured things, it cuts off my breathing. Is there a 'plain' protein powder? I do a lot of plain Greek yogurt. Anyways! Just looking for suggestions or if I'm doing just fine and over worrying.