Emily, I know this is hard but you need to calm down and accept that this process will take quite a while to resolve. I see on another thread that you have contacted the CPS to ask them about your case.
CPS only be on me involved after the police have charged you or raised a file and passed to to the CPS who prosecute in court. There is no way they will know the progress of a sample that was submitted for analysis 3 weeks ago,
In fact the police have up to 6 months in which to either charge you or raise a summons (if you are over the limit) even then it could be another 2-4 weeks before it is served on you.
People have reported on here receiving a summons for drink / drug driving at 6 or 6 1/2 months after the offence.
The police should tell you if the sample comes back under the limit but that does not always happen.
DO NOT start chasing the police for an answer on what is happening until 6 on this have passed.
The danger of doing this is that the sample might have, for example, come back over the limit but is resting in the officers basket to be dealt with and he is off sick. It might remain there until after the 6 months are up and you are off the hook, but when you pester the police and say “What’s happening, what’s happening,” someone goes to ok and finds the result in the officers tray and manages to get the summons raised in time, all because of your impatience..........
I realise it is hard, but do nothing, speak to no one, until they contact you or the 6 months are up and it is safe to check with the police if you want to.