Booster Seat Age Limit Car Seat For A 3 Year Old??

Car seat for a 3 year old?? - booster seat age limit

My 3-year-old daughter in September. The current limit car seat weighs 35 pounds and is almost too small. She is tall for her age, shes 34 pounds and 3 feet 4 inches. Booster seats sought after, I after the age of 3 can be said that to receive them. But I've also heard, no matter what you do not should be in a booster until 4 years. So, what car seat should get when they are over, should not even be in an elevator? I can not give a $ 200 thats a 5-point safety harness for children 3 years now. Suggestions? Is it safe to sit in a booster seat, if it meets the size and weight requirement for 3 years? Thank you for any help!