Just a note that "моя крошка" gives 159000 hits in Google, while "мой крошка" gives only 17200. This word applied to a masculine person sounds really awkward to the native ear. I would not use it so. I would choose the word "малыш" when referring a masculine person.

This is a piece of a poem by Vladimir Mayakovskiy:

Крошка-сын к отцу пришел,
и спросила кроха:
- Что такое хорошо
и что такое плохо?

Notice that to use masculine gender the poet had to attach "-сын" to the word "крошка". Notice also that in the second line he uses non-diminutive form of the word, "кроха" in feminine gender even though he refers to a boy.