This is confusing to me! If I've spotted 24 Froglets, will the next one I spot give me Frogspawn? If not, can someone check out my garden and see what I need to do? I want to do the bottom dwellers, but I'm not quite getting it.

Frogs drop spawn, not froglets.  And you aren't due any underwater frogs because you have had the same number of tadpoles, froglets and underwater frogs spotted in your garden.  For every tadpole you attract, you get one froglet.  For every froglet you attract, you get one underwater frog.

You would have to go back to dry land for spawn.  Whether you are due any depends on how many complete sets of tadpole, froglet and underwater frog (including ghostly ones) you have spotted in other gardens.  You'd then deduct any land frogs you've attracted to your own garden, to see if you were due any more.  I can't see the numbers you've spotted in other gardens, so I don't know whether you are due any at all.

Oh dear!

Other gardens:

Land Frog: 2
UW Frog: 16
Froglet: 24
Tadpole: 18

So that's 16 full sets (the land frog doesn't count) and you've had 14 land frogs spotted in your garden.

So you are due two more land frogs, but you'd only need one (the 15th) in order to get spawn dropped, as long as you remember to leave an empty table out.

Does it matter if it's a low empty platter?

if you are doing bottom dwellers the spawn needs to be on a low table. if you are going to start frog breeding it doesn't matter

however, if you're doing dwellers, I would suggest using SF so you spawn would be SF as well :)

I was just going to say, it depends on which wildlife you want to attract.  Check the Wildlife Guide, and it will tell you which table you need.

For the frog breeding you'd want low tables for froglets, high tables for underwater frogs, either for the tadpoles.

Well, I want to start the Bottom-Dwellers. I don't have any Superfood to use unless I buy some.

I always suggest frog breeding BEFORE dwellers.... both are easier with SF though- just some advice :)