We have one of the Fisher Price Healthy Deluxe Booster / Highchair combos that just attaches to a regular chair, but at 2 years old my daughter is totally over it. She can't climb into it by herself because of the higher sides of the seat, so lately she's just been sitting on her knees on a normal chair.

Should I buy a different kind of booster, or is knee-sitting until she's tall enough to reach the table just the next stage?