Carseat help

I followed the instructions exactly but I can't get this bubble to center. It's making me so anxious. I brought it up to my ob and she said not to worry about it because apparently that tends to happen when the carseat is rear facing, but I still can't help but worry. Whenever I get time I come out to my car to try and fix it but it just won't center.. is it my car?? Should I really not worry?? I looked up where I can get carseat help near me but I haven't been able to find anyone...

Edit: the only way I can get the bubble to center is if I pick the base up about half an inch off the vehicle seat. It's like my only solution is to put some kind of blanket or something underneath the base. But that seems dangerous..