On 6th october i had protected sex with

a CSW. There was a very brief moment when she was on top of me without a condom and i was concerned my penis entered her unprotected. 5

weeks later i tested at a private clinic for chamlydia, ghonnoearh, m. genitalium and trich and my results were negative.

However, the nurse initially asked me to pee in three containers (one for chlam/ghon, one for M. Genitalium and one for Trich) as the guidance from the lab was that the containers would be going to different departments (so i assume meant they didnt want to risk opening the container in one and risking contamination or something)

This is a well known lab used both by the NHS and well known private health clinics in london. Do you think i need to retest?

Have confidence in your results.  As long as the tests were all run, and they were or results would not have been reported. I would have great confidence in them.  

I will add that the encounter you describe was low risk.  It is not clear that penetration occurred (you would have known, really) and most STIs are not transmitted by apposition.  Further most CSWs do not have STIs and even if your partner did, most exposures do not result in transmission.

Have confidence in your results.  I see no need for additional testing.  EWH