Hi J.-
When my daughter was 10 mo she was also 29 inches. She was also only 17 1/2 lbs...she is petite but tall, making it difficult to get length that fits with a waist that didn't fall off. She was wearing 12 mo and transitiioned into 18 months when she was about 1 yr 4 mo. She will be two in Feb and is still in 18 mo. She is about 33 inches. I'm finding that the 24 mo are really big in the waist. The length is also really long. If the clothes are too long, they are not practical for everyday purposes...the kids trip over them or get tangled in baggy clothes when sleeping.
I did find Cherokee jeans at Target that had an adjustable waist. I believe OshKosh has them as well. It might be worth a try.
As far as how much your daughter will grow, mine grew 1 inch from 9 mo to 12mo...She grew 3 inches from 9 mo to 15 mo.
If you're finding good deals on clothes, just save your reciept and don't cut the tags off until it gets closer to your daughter will be wearing them.
Good luck!