I am supposed to be attracting both types of adult frogs but I keep attracting mermaids or red caterpillars. Please help

You aren't due any underwater frogs as your numbers of tadpoles, froglets and underwater frogs (including the ghostlies) are the same.

I can't see whether you're actually due any land frogs, because nobody other than your friends can see your numbers of wildlife attracted.

If you can list the numbers of tadpoles, froglets, underwater frogs and ghostly frogs you've spotted in other gardens someone can check whether you are due any of those, or if you'd need to do some more spotting first.

37 tadpoles, 30 froglets, 23 underwater frogs, 1 ghostly frog, 13 adult frogs spotted in other gardens.
93 tadpoles, 93 froglets, 89 underwater frogs, 4 ghostly frogs, 24 adult frogs spotted in my garden 

Since you have attracted 24 land frogs and spotted 24 frogs in other gardens (underwater and ghostly), you are not due any land frogs right now.
If you spot one more underwater frog in another garden, you can attract one more land frog and the 25th will lay frogspawn.

Thank you so much Tracey and Dominique for your help. Sooo confusing, I had forgotten about the ghostly ones x