I'm not sure whether my conversions is missing or not

1. Check is there a delay in tracking for the offer that you are reporting because certain offer has delay in tracking conversions it will be stated on the offer page.
2. Date of purchase the made due to "Cookie Period" validity
3. How was the purchase made via Desktop or Mobile, because certain offers will not track purchases made by Desktop or Mobile which is also stated on the offer page.

If you find all the above points have been complied, upon then you may submit "Missing Conversion" from your dashboard for further investigation by the advertiser.