Blood Tests

Hi! I was wondering how long it takes to find out if bloods came back negative? I was told they would only contact me if something was wrong and if i hear nothing then I've got my next appointment in 3 weeks time. I had some very light bleeding on and off the last two days but i haven't heard from the doctors from my blood test last Thursday?

I've previously had a miscarriage so I know its not like that, its light and no pain. Just don't know if I should contact them or just wait and see what happens.