You are not a failure if you have lost 2 1/2 stone in 10 weeks, you have done amazingly well, particularly on such a restricted diet. Keep going and gradually your bg will come down. Perhaps you should consider eating a few more calories, it may slow the weight loss but it will make the transition to a permanent way of eating easier so all the hard work is not lost within a few months. The winners in weight loss are those who not only lose the weight but keep it off for over a year. Try to keep the rise in bg to less than 2, then about 1.5 when you test two hours after a meal. Without the carbs the weight will still come off but you will start to feel better and more in control around food