Missed period help! Xx

Hiiya! I had the mirena coil fitted in for a month .. N had it taken out before I always had 28 day cycles and I got my periods bk straight away n first period was 28days I think n the last four have been 25 day cycles will they stay like that? Just I'm late for my period by two-three days and getting negative but I ovulated on day 14 8dpo I should of came on? Thanks xx