How old was your LO when they stopped using a high chair? Also any recommendations for eating at a kitchen island counter with a toddler if you stopped the high chair?

We don't have a table, just the counter and backless counter stools, plus her hook on chair. The 2.5 year old always wants to climb and sit on the stools now, but I don't feel comfortable leaving her on them, like I can in the high chair (to get something from the fridge or the other room or go to the bathroom). Thinking about borrowing a regular stool with a back and maybe getting an inexpensive booster type seat that she can be clipped into? We will be moving soonish so it is short term- I really want a real table when we move!