id almost be willing to guarentee *most* of the reason for the slow down is because youve been dieting down so LONG. I hate to oversimplify things and give a politically incorrect answer, but your metabolism has prob slowed to a screeching halt (or "adapted" metabolically to the low calories, with no real change for the past 4.5 months.) Your body has become efficient at working/living off of only 1200 (approx) cals a day, and it doesnt really *need* to tap into fat stores anymore. I hate to say it, but because you (admittedly) didnt workout, ESPECIALLY doing strength training, then youve almost definitely lost muscle mass as well during this period, which once again, is going to lower your metabolic rate. I cant really offer any advice at this point, because the damage has been done, so to speak. The one thing that will definitely help, although i KNOW you WONT do it
is to do a massive refeed week or 10 days, where you eat at or ABOVE your maintence cals, like 2000 to 3000 a day, concentrating on high glycemic index carbohydrates, to rest your hormones and give your metabolism a does of happy happy.
Google refeed, or reload. Its scientically sound and a very very well known tactic in fat loss and in the fitness industry. However, since youve been so low carb for so long, if you DID chose to do a refeed (which i doubt you will, cuz its a scary scary idea) expect to see a MASSIVE scale rebound (of mostly water weight) by the end of the refeed. We're talking upwards of 10 pounds? Granted, it comes back off within a week or 2 of dieting back down, but its really scary to see those numbers again, and to feel so bloated you cant close your jeans.
I did a refeed after i finished MRC because my body was so outta whack, that i couldnt even look at a donought withough gaining 5 pounds. After the refeed i had gained 11 pounds! But i enjoyed that week of eating whatever i wanted
My weightloss had also completely stopped (before the refeed, when i was still doing MRC) no matter what i did, and if i ate above 1400 cals i gained weight. Now i eat lots of carbs, i was able to lose those last stubborn pounds i couldnt get off with MRC, and im able to maintain (with ease) at around 1700 to 2000 cals