I just wanted to share a photo from last year to offer hope for anyone driving themselves mad with cheap pregnancy strip tests. After 2 miscarriages I had an unhealthy obsession with trying to watch the lines on pregnancy tests darken and the lines were often very light and very variable.
I gave up testing after doing two tests from same urine at 5 weeks, top one in the picture was from Superdrug and was not supposed to be very sensitive but was very dark, bottom one from eBay was extremely light, these tests were so light day after day that I started panicking about HCG levels. I didn't need to worry, a healthy pregnancy followed and I am currently cuddling a sleepy baby boy. So my advice would be to put down the pregnancy tests down if they're driving you mad. Waiting for the line to darken is nonsense and tells you nothing about the pregnancy, save yourself the stress.