11mm flat polyp in ascending colon, last csp was 5 years ago and was clear. is this a concerning size and type of polyp for a 29 y/o female whose mom has hx of polyps and dad was dx with stage 3 rectal cancer at age 35? will i always have polyps now?

Not necessarily. But with your family history you need a closer followup and possibly genetic testing

Not necessarily. It is good that you had a colonoscopy. Given your family history, you should get repeat examinations as advised by your gastroenterologist. It may be as frequent as ever 5 years, even if no more polyps are discovered. In between, you should consider getting a FIT test each year. Wish you good health!