Ive been in 7th grade for about half a year now and I started dating this one girl on the 3rd day of school. Recently I decided it wasn't going to work out and decided that I was going to dump her, but then she dumped me. Then I asked a girl out the next week and she said that she was too young to date.
Am I taking this dating thing quite fast?

Yeah, you're too young to be dating. Why can you not just be friends with these girls? Going from one girl to another makes you look desperate. Stop doing that. Just chill.