Feeling desperate :(

Could really do with some words of wisdom please! I'm almost a week late and still getting negative pregnancy tests, I feel like there should be at least a faint line but there is literally nothing! I'm very regular with 26 day cycles, this is the only month I didn't do opks so not sure what happened in fertile week but I generally ovulate around day 11 and we did bd in my fertile week. Surely if I was pregnant I would be getting positives by now? I'm starting to worry that something is wrong? I've been really relaxed about being late and not stressing myself so don't think I'm delaying my period with stress but I'm starting to worry now. Anyone who has had a similar story or anyone with advice i would be so grateful also I do have a doctors appointment booked for Tuesday. Thanks xx