Your back up information is what you can use to get at your account if your password fails or you lose your phone. If you believe that your account has been compromised then you need to check that only your email address and phone number are in there. A trick that hackers use is to put in their information in the back up section so that if you change your password, they will just change it back again later. You do not want the hacker to know you have changed your password for him or her to change it again and this time lock you out.
To check that the information recorded in Google is yours, go to:
Your profile picture > My Account > Sign-in and recovery > Account recovery options