There are exactly zero safe ways to answer your title question, so instead I'm just going to address the issues you've addressed here with some practical advice.
Congratulations on the times you've lost weight, although it is a shame that your weight loss efforts have been followed up with regain afterwards. Contrary to popular belief, keeping weight off is actually easier than getting it off in the first place, but many people stumble because they don't adjust to living at maintenance -- instead they alternate between starving and binging. This isn't a judgement against you, btw, just something that you'll need to understand if you want to make any longterm, permanent changes to your physique. If you want to say goodbye to the current physique and hello to a new physique, you also have to say goodbye to the lifestyle that created the current physique and hello to the lifestyle that will achieve and sustain the new phsyique. If you train and diet and lose 20lb, then revert back to the lifestyle you had before losing the weight, then you'll also revert back to the body you had before losing the weight.
A lot of the issues you currently have can be dealt with through appropriate lifestyle changes. Getting involved in weight-training whilst losing weight, and staying committed to it long after you've finished losing the weight that you want to lose, will do wonders for your body composition. Check my threads in the weight loss stickies for an explanation as to why this is the case, and for an example program to get you started. Those stickies also have basic nutritional information that can help you control your body weight, if you put it to use. Going through the processes I've discussed in those threads will help you lose fat specifically, and build (or at least maintain) muscle. That'll be half of your physique issues dealt with.
Unfortunately, I can't promise anything with regards to your boobs or saggy skin. Maybe as you build muscle and lose fat your skin will tighten up, maybe not. If it doesn't and it's something you really feel needs changing, that may end up becoming a surgical matter. The same may also be true for the boobs.
In saying that, I understand all too well the emotional issues that factor into body image, due to my own body image issues as a teenager, and a couple lapses as an adult. The other day I wrote up a thread about bodybuilding, and one of the important things I put in that thread was a discussion on the emotional/psychological issues that play into body transformations. You may be happier if you lose body fat and become perkier, but if you think your happiness relies on those things, you'll probably never be happy in your skin. In general, people who say "I'll be happy when I just lose that extra 5lb" lose those 5lb, and then find something else to be unhappy about. So, whatever actions you end up taking, make sure you address any emotional issues you have about your body image and work on those issues seperately to training, eating, and (if it comes to it, hopefully not) surgery.
