So Close, Yet (Seemingly?) So Far Away

I am 2 lbs away from reaching my personal goal weight loss that I set for myself way back in March.  I am 2 lbs away from having lost a total of 43 lbs.
I remember when I first set my goal weight.  At the time it seemed so far away, but not completely unrealistic.  Knowing that I wasn't embarking on some sort of a "fad diet" certainly helped to keep me focused.  I changed my lifestyle not only because I wanted to lose weight, but also because I wanted to be healthy & feel healthy.
Mission Accomplished...
However..
As I sit here tonight, thinking about how close I am to reaching that big goal, I feel oddly disappointed in myself...& I really don't have any clue as to why.
I'm several sizes smaller than I was back in March.  I've lost a lot of inches & gained a ton of muscle.  I average walking anywhere between 10-15 miles per week.  I'm eating healthier than I ever have in my life & I certainly feel much healthier, too!  I can chase after my kids & not even break a sweat.  I'm no longer gasping for air when I walk up & down the stairs to do the laundry or to put the kids to bed!  I can walk for great lengths & actually want to keep walking!!  I've had to dig deep for self motivation, but with a few exceptions here & there along the way I've stayed true to my promise to exercise & eat healthy on a daily basis.  I've changed, for the better!, in so many ways...
But when I look at myself in the mirror I see that I still have a lot of work left.  I figured I'd lose 40 lbs & look thin, but I was wrong.  I still have a good 20 lbs of fat left to lose.  I know it doesn't make much sense, but I don't think I ever realized exactly how overweight I had become until I started losing the weight.  I thought when I lost the 43 lbs I'd be content & happy.  My new goal would be to maintain my weight.  Now my new goal is to lose another 20 lbs & I can't help but wonder.."then what?".  Am I going to be content then?  Or am I going to tell myself that I need to lose more weight?  Will I always feel like I'm so close, yet (seemingly) so far away?  I guess only time will tell.  While so many of my family & friends are cheering me (and have been from the beginning!) I'm disappointed that here I am, so close to my goal weight, and I don't feel like celebrating at all because now all I can think of is that I've got another 20 lbs (or more!) to go!  Frustrating!!