Justice, I'm curious about your reasoning in regard to getting a shorter short board at this stage, length has a bit to do with board qualities, but there is so much more that makes a board do its thing. Your previous post says where you are at in your knowledge of boards, so in order to answer your question what is it you looking for in going down another 3"? 7'9" to 7'6" probably not a lot and the length can be accommodated with changes in volume.
Post a picture of the board you have just bought and maybe a name or picture of what the next one you are thinking about.
IMO getting a stable surf education on one board in the beginning is the best way to go, but however you go it's OK, just some paths are easier than others.
One thing about justice in most democratic countries is they don't allow double jeopardy.

o my advice one board at a time!