Sort of newbie... with dilemma

Hello, my name is Laura and I'm from Italy.
I'm not exactly new as I've been on MFP for over 100 days now, but I never introduced myself.
I found out this web site thanks to a friend of mine, and it has been great to help me lose the baby fat that was slowly crawling all over me after my second child was born. It wasn't much weight, around 20 pounds, and I almost felt ashamed about it as I have read some awesome success stories about serious weight losses from you lot! But for me those 20 pounds could have slowly gone up, and up, and up... and they were slowing me quite down... and depressing me.
In any case, in about 3 months I reached my second target (I initially aimed for 55 kg - 121 pounds, considering my age and two pregnancies, but as I seemed to reach it "easily" I decided to go for my pre-children weight of 52 kg - 114.6). I actually decided to stop at 53 kg (116.8 pounds) in the end, as I was happy enough with the results, and are now aiming at maintaining (my TRUE challenge).
This last week, even if I was careful to eat as many calories as possible, including the ones burned in exercise (mainly walks with dog and gardening) I found I lost almost another kilo (2 pounds) and I believe that is what left me last night with a desperate craving for sugar! As I had lost weight I hadn't planned to I gave in to the desire, and don't feel bad about it, and today I'm easily back on track.
But I wonder if there is something "wrong" with my metabolism that doesn't keep me in maintenance mode, and makes me lose weight, that then triggers sugar cravings..! I would love to start some toning exercises (to be done with a DVD at home before the kids are back from school), but what if I "burn too much", and even if I eat it all back the sugar cravings start again?!
This is my dilemma...
I had already managed 3 times in the past to lose all the extra weight (once with a dietician's diet, once turning vegetarian - long slow process, and all the weight came back in a month as soon as I started eating meat again! - once with WW). And I have been "dieting" since a teenager. Now I am thrilled by MFP as I can lead a normal life, exercise, eat what the whole family eats, and eat some sweets when I have had an especially good day. But I'm afraid to put it all back, like in the past, due to those pesky sugar cravings!
Your wonderful stories have helped me so far, and I hope they will keep doing so! And if anyone of you out there has some suggestions, I'll be glad to hear them :-)
Thumbs up for MFP, and it's wonderful community!