can't help too much as far as what is required re qualifications etc in your area, and you might want to list what state you are in so that others might be able to assist you further, but as far as age goes....
I know of a lot of people who joined the job older than you.
It all really depends on who you are and what you can do, not how old you are.
There are plenty of people younger than you that should no be in uniform. If you are healthy and fit, and can pass the requirements and are deemed suitable, then neither being female nor your age, should prevent you form being able to do the job.
As long as you can keep up with those around you, age nor gender do not come into it.
best of luck
"He didn't want to tell the cop he was on his way to the Butt Pirate Palace for a little two-step with Joe-Joe during the Village People marathon." - Cat_Doc
"Cause when your hourglass runs out of sand
You can't flip it over and start again...Don't blink..." Kenny Chesney
"Take care, never leave home on bad terms, watch your back and go home in one piece." - Aussie Nathan
"The batton in my jacket is hot like a porn actor to beat someone down." - Patchcop