Congrats on almost having a year!
I'm coming up on 8 months sober in 10 days. I changed sponsors about 3.5 months into my recovery. My first sponsor just wasn't available for step work and canceled on my multiple times. I just said I wanted to go in a different direction and thanked him for his help.
I didn't have a new sponsor already lined up, but I had a short list and asked someone new within a week.
The truth is, sponsors just want to see you doing well and sober. They will not take personally. This isn't a romantic relationship. The number one goal is to help another alcoholic stay sober. If moving on to someone else will keep you sober, no one will give you a hard time. I still see my old sponsor at meetings sometimes and we chat. No hard feelings at all. He's just happy I'm working hard and making progress.
Good luck!