Have you found the low sugar box? Ask the store if they carry it. I got some Ball low sugar at
TSC.
I do not like the 7 cups either. The low sugar is not saccharin or nutrasweet, it is just higher pectin.
I think it makes a nicer jelly because you get more fruit flavor.
I also suggest that you get yourself a ball canning book. It has more than just recipes in it.
It covers pressure canning and jellies.
I am impressed that you have decided to pick this hobby/lifestyle up. It is work but fun work. and it is very satisfying to eat what you grew and preserved.
I get very happy on those rare days when I look at the dinner table and realize that everything on it is mine. I grew it/saved it/ served it.
As far as the PC goes and knowing if it has gone bad,:
If the top is popped, don't eat it.
If it seems slimy or different than the others, don't eat it.
If it smell off ~ don't eat it.
If in doubt, throw it out.
I have canned pumpkin when I have had a bumper crop. We Floridians usually do not have cellars. around here they are called swimming pools... Something about living on a giant sandbar.