With all due sincerity I will take a stab at this, but my situation is rather different than yours -- I'm a 50 yo man but I was able to sucessful shed 30 pounds in about 3 months. I mostly took the calories in less BMR less fitness calories burned approach and that worked perfectly well. Here are more details, some perhaps unorthidox: I drank 64 oz of water everyday. My breakfast was a power smoothie (check Amazon for Superfoods by David Wolfe) a regular sized lunch and portion controlled dinner. My exercise was running and resistance bands, both for the burn, afterburn and time efficiency (I'm busy). I also did a herbal detox and herbal colon cleanse at the outset to get my pipes clean from the start (and I felt great afterward). During the three months I also took an acai berry supplement from Costco, drank a daily Costco weightloss shake (200 cals) and for about 3-4 weeks took hydroxycut.
I hit my goal in late June, actually shot past it (too far) but have normalized for about 3 months just below my goal weight. So I guess it worked and still works (I don't take any cleansers or weight loss products any more of course and just eat normally). I don't drink coffee any more (plenty of energy) and don't smoke or drink (ok a couple of parties along the way...).
I think the "starvation hormonal theory" sounds most plausible to me if your calorie counting is accurate. Your BMR must be rock bottom (mine's 1680). I feel bad for you because you sound VERY disciplined and I admire your tenacity. Another question just came to mine -- are you getting a full eight hours solid sleep? That will impede your weight loss (and add to stress) if not.
I have been running since early April. Running about 30-35 miles (5-6x) per week. In the last couple months I've introduced speed workouts (tempo runs, intervals, reps), mostly on the track. I've notice in the past 2-3 weeks I'm experiencing tightness in my left inner thigh (the adductors). Butterfly stretches, icy hot massages and easy warm ups seem to do the trick, but now I'm wondering about muscle imbalance and whether I'm on the path to a strain or tear or maybe this is just simple over training...I don't know. I'm 50 and feel great on my runs (39 minute 10ks) and have no other injuries/physical issues besides this.