Moses Lake Police shared a video recently saying they see this mistake all the time. Despite your best efforts, you could be endangering your child:

The rule is knowing the weight limits on the anchor restraint belts. The LATCH systems in cars (anchors in the car where belts on the car seats can latch onto) are easier and safer than the seat belts. But the anchors are only good for up to 20-25 pounds INCLUDING the car seat. That means they should only be used for very small children.

If you use anchors AND seat belts you should be fine. But if your 18-month old child is still secured by anchors alone, your baby could be in serious danger in a high-speed accident.

Fred Goldstein