Stuck at 200lbs and scared of falling off the wagon

Hi The first three months of my weight lost went brilliantly and I was meeting if not exceeding the 2lbs a week without effort, entirely through calories with no specific extra exercise besides taking the stairs etc. For some mysterious reason decided to have a couple of weeks off, which turned to 10 weeks, during which time while I didn't gain much I could/should have lost at least another stone. It was realising this that made me continue the plan. When I resumed NC it was the start of May, and within a month I lost another stone (including a lump of 6lbs at the start which covered the 4lbs that I gained on the break). The problem is since then I have been the same weight - give or take a fluctuating pound. To try and get me on the right path again I have tried eating less than I am meant to, eating more (but healthily, not binging), having more water (though I already got my 2 litres) and most recently, exercising. I have been doing a workout program for the last four weeks now which involves cardio as well as free weights and gives me 200-300 cals every week day and I have been taking walks on weekends. While I have now been doing muscle workouts I am not sure that accounts for STILL not losing anything, but maybe it does I am not sure how it works or how easy it is to gain muscle. I have tried eating my exercise calories back (which I believe you are meant to?) and not and haven't seen a difference. On the advice of a friend who suggested I might be losing size not weight I have done measurements for the last two weeks and I "only" seem to have lost half an inch on my waist with no change anywhere else. What is most baffling is that I have lost weight without exercise before just through counting calories and when I was a healthy weight and never had any problems - now I am still classed as obese (albeit only by a couple of lbs) so unless being 3 years older (but still in my early 20s!) is really a massive factor in this I can't understand how nothing is shifting no matter what I do. After 12 weeks of no progress I am finding it hard to keep morale up when my target gets further and further away and the sudden drop I was expecting weeks ago never comes... Sorry for the length of my post but I am reaching breaking point, and am scared I am on the verge of completely falling off the wagon. I enjoy being healthy and the exercise has made me a lot fitter but health was meant to be the by-product and not the goal. Thanks