Periods

So I've been having some really weird things been happening king my body and I'm hoping some people have experienced the same things and can help me out. Anyways I'm on birth control I take it every night me and my boyfriend use protection, but my period has been very off lately. It has been 6 days late to 13 days early to right on time but only bleeding for one day. I'm starting to get really nervous because I've been bleeding on and off on random days and my flow isn't heavy at all like it used to be it's also not a red blood it's more of a brown-ish colour. Does any one have any advice? TIA