Yes, you have thread tension problems, and it's probably because the machine isn't threaded right. There should never be that much difference between the top thread and the bobbin thread. Are you installing the bobbin correctly? That's what it sounds like.
Look at post 3, 4, and 5 of this thread: Singer 211 issue, bobbin case? - Hot Rod Forum : Hotrodders Bulletin Board
The picture shows how to thread the needle thread.
Size 10 is too small for auto upholstery. I never use a needle smaller than size 18. The thread size should be at least size 69. I don't think size 69 will even go through the eye of a size 10 needle.