Amy from the big bang theory has changed a lot over the years

Watch her early episodes like the one where the girls have a slumber party. Amy talks with a monotone robotic voice and mannerisms, where in the past 2 or 3 seasons she seems more like a normal woman. It's almost like having friends changed her life for the better and she stopped being an awkward loner. Even sheldon has changed since season 1 although he's still a control freak. Speaking of changed, whatever happened to leslie winkle and priya? they just vanished and were never heard from again. It would be nice to have one of them back but that would make the already crowded main cast even more crowded(amy,bernadette,penny,raj,howard,sheldon,leonard and stuart). I'll keep watching this show until it ends just for the guys