I can't seem to lose weight no matter how strict I am? At most I lost was 20lbs, when I was pregnant. 5lbs when I went on the p90x. Whats wrong?

Complex answer. You should first have a metabolic, including thyroid evaluation. If these are normal, the answer is still complex. Not every diet type works for every person. Bmr, basal metabolic rate, is a measure of how many calories your burn at rest and is variable. The best way to boost yours is some form of muscle conditioning. The more lean body mass, the more calories you burn at exercise and rest.
Check BIA. Check your bia it will tell your lean mass vs fat mass. Even though you might think you are not loosing weight might show as increase in lean mass - what is your weight loss goal? It is important to keep doing the program that works otherwise there would be rebound weight gain.