HELP are car seats supposed to do that?!?

Our American car seats do that. It is called rebound and it perfectly safe. The only thing you need to check for is to make sure it is secured at the BELT PATH. It should being moving less than an inch. I would say that an inch is too much. Some convertible carseats have a rearfacing tether such as certain Britax brands and some Radians, but the tether is not required (although, highly recommended).

Edit: Since I know that 95% of car seats are installed incorrectly, I would go to a CPST (Child Passenger Safety Technician)

Kind of. In an accident, the seat will tip to the back of the rear seat but shouldn't go to much. Look for a Safe Kids site or a car seat tech in your area to check fit. It is perfectly fine to move that way, just not side to side more than an inch. We still have our two year old rear facing, don't ever worry about 'legs too long' or 'too scrunched up'. Kids are pretzels, and will only break a leg if they are forward facing. Rear facing is safest to around age three.

http://www.youtube.com/watch?v=sssIsceKd6U here is a video that pretty much shows how a seat moves in a crash.

Safe Kids http://www.safekids.org/safety-basics/safety-resou...

A car seat tech will be a better help since we don't know what car or car seat. Sometimes pool noodle or a rolled towel will help get abetter secure fit.

Call your local police and ask whether they-or any other agency in the area-checks car seats for safe and appropriate installation. Then have it checked as soon a possible.

It should NOT do that. A correctly installed car seat should NOT move.

Take it to a fitting station and get it checked.

Carseats shouldn't circulate better than one inch on the belt course (the place the seatbelt or latch strap is going during the backside or carseat). the different circulation (in the direction of the back of the backseat) is stated as rebounding and punctiliously wide-spread. in case you won't be in a position to get it tighter than decrease than one inch of circulation on the belt course, then you definately could desire to locate a carseat tech (CPST) to coach you training on the thank you to place in it appropriate.

I agree. Get it checked but it sounds like you have the straps wrong even if it looks right you probably have them switched even any nurse at your OB clinic will show you how to install it...

I would take it and get it checked by your local fire department or American Red cross.

Get it checked just to be safe!