Wow, 96 lbs?! I see why you are striving so hard to reach that 100 lb mark, but you have done amazing work so far! 18 months of maintenance is a remarkable feat in itself. I'm sure you will break this plateau!
I am just throwing this out there but if this is a mental thing, you could try to lower your goal and trick yourself. Set a new starting point from your current weight for another ten pounds.
I'm so with you. I started this saying at like to lose "about 100 lbs" and see where my body would settle on. Well I got to that 100 lbs in Sept 2010 and picked my final goal of 145. And instead I seem to be fighting gaining and losing the same 5 lbs. Is it my body telling me this is the right weight for me? Or did I lose my focus after acheiving the 100 milestone? I really can't say. I'm really happy to be maintaining a monster weight loss but keep thinking about whether or not this is "it".
I'm wondering that with the 175 for me. My initial goal was 175. I got there the beginning of December and I decided I could lose more and get down to 160 and I still feel that is doable. I quickly gt to 171 and then the holidays hit... Up I went... And then started to come back down and then it started to go back up again.
Notice it's right at the 100 total pounds lost... What is up with that? I was losing so well and then bam....
The 100 lb curse!! So it's not just me. I'm sitting here with my finger over the trigger to change my goal to 147... that just seems so weird... I have no concept of that number haha.
I concur with reducing your goal a bit, I think it's you psyching yourself out with 100 pounds and a LOT of us do that! I have the same start weight as you and am worried about the same thing, because I know the mental games I play! It's often not intentional, yet the effect exists nonetheless.
When you have lost that significant amount.....your mind - your eyes - your brain - your emotions - your whole being - has to catch up. Do you yet catch yourself in the mirror sometimes do a double take? Do you think "hmmmm....I really DID lose weight." "I AM thin." Or, dreadedly, sometimes think "I'm not done yet....there's more to lose...ugh I look fat today?"
I think its normal to just take a moment to "be". You know this is forever. You haven't gone back to horrible past habits and regained any significant amounts. You've put a few on, took a few off, and that is normal. That's what happens to everyone. It could be a night of chinese food laden with sodium or clogged pipes or TOM for us chicks....but we fluctuate. When you've seen a small increase, you've managed to nip it in the budd.
IF you get serious about losing more, you know how to do it....just eliminate a few daily calories. Doesn't even have to be much--you're basically maintaining on what you're doing now...so eliminating a few will eventually make a weight loss.
Don't sweat it. You're figure looks amazing, and you have a gorgeous face. You'll be dieting for the remainder of your life....and if you want to be just a little lighter, you'll muster the strength to do the necessary. You have all the tools and knowledge.