Opk not getting darker

Kerrie
Hey ladies. I came off the pill Christmas Day 2015 and have been TTC #1 since then. My periods went straight back to normal with a 26-28 day cycle and a 4 day period. This month I've started tracking my BBT and using ovulation tests. I know my BBT spike will only tell me if I have ovulated but I've been using ovulation strips everyday between 2-3pm with at least a 2 hour hold and very little to drink since my period finished (as this is my first time) and they have not been any darker than the picture below. I am now on cd 13. If I'm on a 28 day cycle then logically I should ovulate tomorrow right? With a 14 day luteal phase following. But the strips aren't anywhere close to positive. I don't really know what my question is I'm just looking for thoughts really. Worried I'm not actually ovulating yet having been on the pill for 13 years. Thanks in advance and baby dust to everyone x