It sounds like you need more time if you want flowers to grow. Most of them don't thrive on neglect. Desert Rose is a good one that doesn't need water, but it needs winter protection. Crown of Thorns would work too, but they don't like frost. Blue Porter's weed is a nice blue spiked flower that blooms all the time and doesn't need care. Frost would hurt that too.

Plumbago

Daylilies fit the bill and flower constantly from May to end of September. Best in full sun. If you have some shade, if you mix in some organic material when you plant them, semi dwarf azaleas do really well and will flower constantly from August to May. ( where large azaleas only flower for about a month) This will give you flowers all year on cold hardy plants. Floribunda roses sometimes grow a little wild if you don't trim them a bit, but they will push flowers'all the time when its warm and there are ones that don't get the bad fungus problems that hybrid teas get. That will get you started anyway.

I agree with the plumbago and also a Jasmine takes the cold pretty good. I'm sure there are others but that is off the top of my head.

Thanks everyone!

Sedums. Moss roses. Gerber daisies. Tradescantia pallida. You might get away with Pentas.

Some of the things that are low care in cooler areas don't last long in FL. I've had bad luck with sedums for example, just melt away. I'd suggest Siam tulips (Curcuma alismatifolia). They mix well with amaryllis and bloom at a different time. And they are dormant when the amaryllis are in bloom. Crinums and rain lilies are also very low care, they like being left alone best and are well suited to central fl. My rain lilies bloom from June to Nov, I've got common z. candida.

Bulbine blooms almost non-stop and does well with neglect. I like the yellow the best, but it comes in orange & yellow too. Fills in nicely. I've thought about using it as a ground cover.

Bouganvillia survive neglect,assorted bromeliads do well just left alone and almost always look good. Vinca need some pruning but are hard to kill.

Mexican petunia aka Ruellia brittoniana is very hardy, pretty and comes in purple, pink or white - nice, tall and requires NO CARE at all.

Gaillardia or Blanketflower is a good 'plant it and forget it" flower. I planted some seedlings last spring and around October they were finally big enough to bloom. And they haven't stopped. Even on the recent mornings where I've had frost weighing down the burned stems of other plants, the Gaillaria has been quite happy and seems to have a new bloom for me every other day. They're not very tall, but over time they will sprawl across the ground like a blanket. And a bonus is that they self-seed. So even if I do lose one to frost (not likely from what I've seen so far) there should be plenty of offspring ready to take over.

Ruellia is a class 1 invasive in FL.

The Asclepias (butterfly weed) suggested in the link instead would also thrive on neglect.