Telly, if you are doing enough resistance exercise (weights, etc) to maintain your muscle mass, then don't worry about going lower than your original goal. It's easy to gain back a few fat pounds if you ultimately decide you're too thin, but wicked hard to put back on the muscle. It might be worth it to get your body fat tested, too (by a BodPod or other accurate, professional method, not a body fat scale). Anything over 20% and you are not too low.
I think Saef's advice is excellent - take a hard look at what you really want. "Too skinny" is so subjective. I would think if you lost so much more that you had to buy all new clothes, that may be too much. Otherwise I think body fat % is a fair judge of too skinny if you are not an athlete. My DH (who is 50 lbs too heavy) said I was too skinny 15 pounds ago. I told him if he wants a plump woman he'd have to find a different one
I think he's finally getting used to my new look.
It has taken me about 10 years to come down from 184 to 125 pounds. In all that time I never regained more than a pound or two, but there were long periods of time when I stayed around the same weight. My motto was "If I'm not trying to lose, I gain", and that was basically true but I came to realize that there are various levels of "trying to lose". Some actually work and some are just a form of maintenance with built in fogetful eating. Now my approach is to track everything, try to hit slightly under maintenance two days a week, and allow one day for over maintenance if my hunger level dictates. It's actually getting easier. I still have a fear of gaining, though, even though I'm not gaining.