Hi and welcome to EM2WL! We are so glad that you've found your way here!

Yes, you have been greatly under eating. The first thing you need to do is calculate your TDEE at the Scooby website here (http://scoobysworkshop.com/accurate-calorie-calculator/). Your TDEE is the total amount of calories your body burns in a 24 hour period including all your exercise. You have a very high activity level, so when entering your numbers, make sure to pick at least the moderate activity and possibly even the strenuous activity level depending on how long your workouts last.

Since you have been eating a very low calorie diet for over six months, you would probably benefit from a full reset. This would mean slowly increasing your calories until you reach your maintenance level, or your TDEE. Once you reach that number, you would continue to eat at that level for minimum of 8-12 weeks. Then at that point, you introduce a small deficit to begin losing weight again. You are going to find that you will need to increase your calories a substantial amount! This is a longer process, but very worth it in the end.

There can be some initial weight gain with this process and it is to be expected (mostly water weight), but adding the calories slowly will help minimize this. You could increase by 100 or 200 calories every week...just take it slow and maybe even stay off the scale if you thing the weight fluctuations will bother you during this time.

You may also benefit from decreasing your workouts a bit during this time. You state that you exercise plus heavy lifting 5-6 times a week. That's a lot, especially if you are doing both every day! Maybe decrease down to 5 days a week, but alternate days so that you're not doing cardio based and strength on the same days. Overdoing exercise can really cause a big stress on the body, as well as the stress of dieting, so your body has been responding to those stressors by plateauing.

The best way to reach this higher level of calories is by eating full fat cheese, milk, peanut butter, butter, olive oil, coconut oil, eggs, avocados, nuts, lean meats, etc.. No need to eat low-fat or low calorie items anymore.

There are some great posts in these forums that will help educate you on the reset process and you can also check out the EM2WL website www.eatmore2weighless.com for other helpful guidance. Be sure to post back and let us know how you are doing and if you have any more questions! Feel free to add me on mfp for support as well.