Weird period

Hi everyone,
I have a situation I'd like to run by you all just to see if I'm clutching at straws.
First of all, my period was late. My cycle was 39 days this month and I really thought we had done it.
I was waiting for my husband to get back from his training course on Saturday before taking a test, and on Friday my period started.
Usually my periods last about six days and are heavy to start and I can see physical signs of shedding (lumps etc).
This month it lasted four days, was heavy for a day and then light, then spotting for the last two days. There was nothing visible other than blood and I've read that you can still bleed when pregnant.
Am I clutching at straws? Or should I test?
Has this happened to anyone else? I have had a cold. Could this have affected my flow.
Thanks :)