However, it is also possible, if she doesn't drop fry, that the female's girth is because she has dropsy. Please check on the Immediate Help link on the upper right corner of any GL page and look for dropsy. That dropsy might be because of aquarium conditions (isolation tanks are harder to keep clean) or also, just because she is an old guppy. Getting older, with a lot of creatures, may mean that the immune system isn't what it once was.

You were wise to isolate her when she became so combative. The color in her unpaired fins is great. However it may be that as she got older (elderly for a guppy) that a not entirely rare mixing of hormones took place. As she perhaps produced a bit more testosterone than she needed, she might have been rendered sterile and a bit more colorful, though colors like those often decorate fertile females.

Fish never stop growing throughout their lives. The growth rate does, however, slow down considerably after young adulthood. Her size, behavior and health issues (if there are health issues) may just be results of aging.

As for your English, it is beautiful, though not so beautiful as French. :)