I agree that your calories are far to low especially if you are trying to train at a high intensity. Don't think I could get out of bed on 800 calories! What type of exercises are you using for your weight training. I would suggest you focus on working the whole body 2-3 x per week using compound exercises such as squats, deadlifts, clean and presses, snatches, bent over rows. pull ups etc. Then you could include 1-2 days of high intensity cardio to improve your anaerobic fitness using sucjh things as sprints, hill repeats, circuit training etc. Don't forget to work in some rest days into your routine as this is just as important as the training.