Superdrug 99p test sticks - trustworthy ??

Hi all!
I was a week late in May (put it down to stress of starting an awful new job, although never late), now June and July's have been completely missed. I have done a few (a good lot more like) tests over this time, most just the uncased sticks from Superdrug for 99p and about 95% of them have come up with a faint line, however I've also done Clearblue, First Response and Tesco  but those have all come up negative, Doc also has done a urine test which was negative as well. Have been reading a lot online - personal stories, research etc...
Not very sure what to do, should I just keep waiting until one of the more pricey ones come up with something and it will be "certain". Hubby and I are TTC and have been trying for 10 months, so would really love it to be the case but all these faint line and negatives are just a gloomy shadow right now.

Thanks