'Corpus' means 'body'; it does not refer to the flesh only, the ordinary term for 'flesh' being 'caro'. Although it is feminine, I employ 'meo' in agreement with 'sanguine', since it is masculine and when an adjective (including a possessive adjective) qualifies two or more nouns it generally agrees with the nearest noun. There are exceptions to this rule, but this phrase is not one of them.

The dative is also possible (i.e., 'carni et sanguini meo'), but in the context of a tattoo I suspect that 'pro' + the ablative is preferable.