Please help!

Lee • Mommy to 3 year old girl! Baby #2 joining us March 2016!!!
Any input would be greatly appreciated!!!
​So I had very minimal spotting yesterday morning and have had nothing in almost 24 hours (with using tampons)! I don't think it's implantation  bleeding because I think I ovulated around the 4th (so 15 days ago). Could this spotting and no AF mean I didn't ovulate at all?