Hi thanks for your question.
You having light periods and some spotting after ovulation and you think your pregnant and this spotting could be implantation
The best way to know cause of this delayed bleeding is to wait for your due date, if bleeding doesn't occur, wait for one week and go for home pregnancy
test, if it comes positive, that means your pregnant.
If test comes negative that means you’re not pregnant.
Menstrual bleeding pattern of the women do get changed normally without any reason, but it is better to consult a physician and get yourself investigated for any pathological cause of change in bleeding pattern.
Hope this answers your question.