Maybe they're uncomfortable with the "new you" because you likely behave more differently now (confident, outgoing, optimistic, etc) and they're just not used to it yet.

Maybe they were drawn to the "old you" because they could relate with you on some level, but now that you've changed, they're having to adjust how to relate with you.

The girl, maybe she was interested and maybe she was being friendly. You'll never know until you ask her out

Many people don't like changes and as rude as they may have been, it may be more to do with not liking the change than not liking the new you.

I knew a guy who lost more than half his weight over the course of a summer. Everyone commented on how great he looked. He felt like the added attention was superficial, as he was still the same person they ignored before summer. So for a bit, the compliments he received did not get internalized as such.