I only get my menstal cycle once a year in july is that okay?

No. Unless you are on medicine to purposefully make that happen, it's unsafe to a woman's health and possibly life- threatening to menstruate once a year. Discourse this with a board certified reproductive endocrinologist.
PERIODS ONCE A YEAR. Actually it depends what age you started your periods and has it always been like this once a year or it was normal before and it changed.Irregular periods at age 18 are not that uncommon, and with time they will get regular. If it is a cocern you should see your gynecologist and only way to regulate is to go on birth control pills.