Menstrual Irregularity: Seeking Answers

I personally haven't struggling with not getting a period anymore, but I have always dealt with reproductive issues and abnormal cycles. The cycles can go 1-3 months in between and even last just as long when they do start. I've never had any tests ran so I can't give insight on that aspect, but just relaying I've always had reproductive issues my entire puberty life. The doctors haven't indicated they had concern about it, therefore I haven't explored options as to why this happens with me.

I saw in my tests that my prolactin levels really vary a lot but I literally have no idea what it means. I have an IUD so I don't have regular periods but before the iud I was very irregular and heavy my whole life.