Hi CoilQueen,
Hopefully you’ve had the chance to read the mattress shopping tutorial which includes all the basic information, steps, and guidelines that you will need to make the best possible choice … and know how and why to avoid the worst ones.
There is more about innersprings in this article and in post #10 here and as you can see … coil counting can be more misleading than helpful. The knowledge and experience of the retailer or manufacturer you buy from can be one of the most important parts of successful mattress purchase (especially when you are "outside the averages) and would be much more important than the number of coils in any particular mattress.
There are also some general suggestions in post #3 here and the posts it links to that may be helpful for those that are in higher weight ranges.
Unfortunately nobody else can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved for anyone to be able to make specific suggestions for someone else based on specs (either yours or a mattress) or "theory at a distance (see mattress firmness/comfort levels in post #2 here).
If you let me know your city or zip code though I’d be happy to let you know about any of the better options or possibilities I’m aware of in your area.
Phoenix