my mom only lets me keep about 10 every month to eat
That's the first mother-enforced-catch-and-release I've heard of, and God bless her for it. The big sunfish you caught is most likely a female, and the largest females of any fish species produce tons of eggs. So by releasing that one you put back a prolific breeder that also has good genetics to pass on to all the babies she puts into the lake.
For the C&R record Mike is talking about, you'll need to get a girth measurement as well, so have a tape with you the next time you catch that robust redear and you'll be set!