What should be a realistic rating goal for me?

I've started chess because my friends were playing chess, and after a year I am 1300 in rapid, 1100 in blitz, and 900 in bullet. Assuming that I play 1~2 rapid games a day, what rating should be my goal?

Don't set rating as a goal. That will give you a wrong fokus in your games.

Your goal should be to have fun playing chess and improve by analysing your games and studying chess. Rating will improve along.

The most important thing for you should not be the rating but the "journey". Most of us play chess for fun. You should focus on improving your play and on having fun. If you really want a rating to be recognised as good player than 1800-2000 should be your goal.

@1

"Assuming that I play 1~2 rapid games a day, what rating should be my goal?"
1500 in short time by blunder checking before moving.
2000 in 1 year is possible, but only with hard work.

your rating goal should be to get higher.

Very easy to get to 2000. Instead of play, try analyzing grandmaster game positions by setting them up on a real board and figuring out without an engine why they played what they played. And also basic endgames.

This book is good ->

Chess: The Art of Logical Thinking: From The First Move To The Last

No it is not.