Pregnant or just irregular period?

Ok, so I’ve only been off BC since April and my cycle is still trying to figure itself out. My last period was 10-11th July (super short) and I finally got a positive opk on 29th July so I know I was fertile around end of July. Now, hubby and I are going with the NTNP method and tbh the positive opk took us both by surprise as every single one previous had been negative.

According to Glow and Premom I’m 3 days “late”. I don’t know if this is because my cycle is still irregular coming off the pill or I could be pregnant. Just wanted peoples opinions before I go and waste £10 on a PT...they’re not cheap in the UK 😂

Did anyone else experience this off the pill?

Thanks x