Is this an evap?
I had a similar line in may and it never got stronger, but I ended up being 2 weeks late then and then bleeding clots, Dr said it was an early miscarriage and I bled again 2 weeks after that.
I know clear blue are a bit rubbish for evaps, can't can't a different one until tomorrow though and don't really want to test again until Friday when af would be 7 days late