hello there.
Well done first of all, what an achievement. 21lbs is fantastic- don't give up after all your hard work.
What can you do to make yourself feel really rewarded (and pretty)? can you go and get your hair done, or have a facial? if you can't afford to get it done, go to boots and stock up on some treatments and give yourself a spa night after the kids have gone to bed (if you have any that is!). Or reward yourself with a walk on your own (can you tell I'm a Mum?!)
Build a picture of yourself at 'target', try to imagine yourself in something really outrageous like a gold lamé bikini (or it could just be that really nice dress you can't get into anymore)- think how fab you will look, now ask yourself: how do you feel? what are you doing? how are you talking about yourself? how are you holding yoruself? etc....
then ask yourself- what is stopping you from being 'that' person NOW?
Once you go through this exercise you will find your answer as to why you are sabotaging yourself. You deserve to be the weight you want to be, you deserve to feel pretty.
Recognise that you have started the journey and that you are doing REALLY well.
Good luck- hope this helped.
Sarah