I am also at that in between height. I turn my average pants up one hem then tack it up. For the petites I take the hem out and turn it back up half way. That gives me an extra 1/2"-3/4" length. I hem them by hand and it's pretty easy. When we have costumes the girls are going to wear for a while and we know they're going to grow we use clear scotch tape and tape the hem up and then we can let it down again easily. You can see if that works for you. You can't wash the pants and leave the tape on though, you'll have to take the tape off and retape it again. This is sort of a try it and see if this length feels good and works then hem it by hand.
The thing about pants is this. The average height fits nearly an inch longer from your belly button down under the genitalia then up the hiney to the back waist. The petite will fit lower and better if you think about it you can determine if the petite's fit better or too tight.
I like having the petite sometimes because the pants don't hang in my crotch. But if they don't stretch the right way then I want that extra length of the average.
Women's clothes sizes aren't hard. They used to be very defined and now they're more generic.
Juniors were made slim. For younger women/girls who hadn't had kids yet and still had narrow hips that hadn't born children. Juniors were the odd number sizes. I wore a 9 or an 11 in high school.
Then a ladies size was a narrower waist and fuller hip for those who'd had kids and spread their hip bones out a bit. Ladies sizes were only even numbers like 6, 8, 10.
A tall has at least 2 inches more between the crotch and the waistband where the petite might have 2 inches less in that same area. The inseam would also be longer or shorter but the biggest difference, that you would notice if you were tall and tried on a short is in that crotch length.
So for your height you should be able to try on the same pants in both average and petite and see which ones feel better that way then address the length issue separately.
Taking a hem length off an average is pretty easy but turn them up and pin them then put on the right shoes and walk around in front of a mirror. If it's too short when you take a step you need to take the hem out and just do it half of a hem up.
I buy almost all my clothing at Cato Clothes. If you have one in your town you can go and find lots of clothes under $10 on the clearance rack. I pay maybe $24 for a new top and $16 for pants? They do have a lot of stuff that is fun and comfortable.
http://www.catofashions.com/?gclid=CM-dqs-lgMECFTOZMgodn0...