Is the step interphase I after prophase I in meiosis I?

No. Prophase I means prophase of the first division of meiosis. It is followed by metaphase I, anaphase I, and telophase I. Likewise the second division consists of prophase II, metaphase II, anaphase II, and telophase II.

Interphase is just plain interphase: no I or II, as it is not part of any division, but the stage between divisions.