'After' is a preposition. It has to be followed by a noun, for example 'after me', 'after you', 'after that', 'after the lesson', and so on.
'Afterwards' - note the letter 's' at the end - is an adverb. It doesn't need to be followed by anything. It just tells you when something happens.
For example, you can say:
We played cards after dinner.
We had dinner, and after that we played cards.
We had dinner, and then played cards afterwards.
In your example, your main sentence should be 'It is your turn' - note that we can't omit subjects in English in the same way as you can in Spanish. The simplest way of saying your sentence is 'It's your turn after me.' or 'It's your turn after mine' or 'After my turn, it's yours.'.