Booster Seat Height Requirements Booster Seat Requirements In Texas?

Booster Seat requirements in texas? - booster seat height requirements

My daughter is 3, March, and I wonder, can in Texas, use the base as soon as it meet the requirements of weight and size? And my car is older and has that a booster seat belts, I can only work with a lap belt?

Here is a site that is http://www.infant-car-seats.com/cgi-loca ...
Do you think if my child will meet these standards be safe for them?