Need help

I need some help. Me and my boyfriend have been ttc for 7 months now. I started my period on July 7th but it was spotting at first. Then it was normal til the 11th. Then for the next 3 days after that I spotted (which has never happened to me before) ever since we decided to ttc my periods at first were 35 day cycle, 3 months ago it changed to 32, then 30 and last month it was 29 day cycle. I'm not sure of the spotting is cause my cycles are changing or what but has anyone been through this or know anything about it??