Which rule to follow?

I am currently attempting to lose weight.  I am quite obese.  I started at 392lbs and am down to 374lbs.  It took me 6 weeks to get to 374 and I have since stopped losing weight entirely.  It's been 3 weeks and I haven't dropped any weight, and my measurements haven't changed.  I eat roughly 1800 calories a day.  On cheat days (about 4 or 5 times since I started 2.5 months ago) I may get up to 2200 calories.  According to every calculation I can find my metabolism should have me burning roughly 3200 calories a day after factoring in sleep and activities.

This means at minimum I'm creating a deficit of 1000-1200 calories a day.  Now I've seen both rules stating I should never go above 2000 calories while trying to lose or maintain weight and also rules saying don't go below 1000 calories.  Have I cut too many calories?  Have I started an unhealthy starvation mode?

I do light weight training 3 times a week and swim at least 2-3 times a week (on the days I'm not doing training).  If I had been putting on muscle I'd expect to see my measurements going down.  Is it too soon to see?  I'm feeling rather down about not losing any weight in the last 3 weeks after doing so well during the first six.

How should I proceed?