Hi there!
Firstly, Rock Bottom is a good place to be! It's only when you get that low that you realise there is no other way but up.... however as you've realised, only YOU can pull yourself back up there!!
I did weightwatchers Jan 2012 and lost about 24lbs by July 2012. I never felt deprived and could fit it into my hectic work schedule (training as a primary teacher at the time!). My weight has fluctuated since then... but everytime I've gone back onto WW I have managed to lose and am back at goal weight now... I am hoping now to lose a further 12lbs now by summer
The way I see it... give it a go! It's not going to make you GAIN weight... and if after a few weeks you haven't lost, then change it up. Its more about changing your lifestyle. As soon as you cut out whatever it is you're eating in excess (for me, it's carbs!) and do some exercise however light to begin with... you will see changes!
Give yourself small goals!! Oh and reward yourself when you achieve them!!
When i first started, I used to put 50p in a jar for every 0.5lb i lost that week... other people use marbles for every pound! Imagine having a pot of 153 marbles and seeing them, week by week, transfering from a ''to lose'' to a ''lost'' jar! Visually it might keep you focussed! I think tbh, it's often less about the diet.... you would know what's good and whats not to eat... and more about do you WANT to and are you READY to change your whole LIFE!?
Good luck hun! any questions about WW then always feel free to ask! People on this forum are always so eager to help, it makes it seem less like a battle when you have that great support xx