How could I test at work?

Hi! I’m 30 and I have a full time job. On working days I leave home at 8 in the morning and I’m back at 7 in the evening (when I’m home early!!) 😵. We’ve been TTC our #1 for 6 months now with no success. Unfortunately with our jobs we don’t have much time and energy to BD during the week so I’m using opk to try and track my fertile days and focus BD. I only saw two peak positive tests when I was on holiday and I could manage to test at least twice per day. When I work I can hardly manage to test once (in the evening) so this isn’t really working. I’m thinking maybe this cycle I should start testing during lunch break at work but I’m not really sure how to do it. To reach the toilets I have to walk past other colleagues (boss included). If I do it for a week in a row with a plastic glass in my hand and spend 10 minutes in there to wait for the result I’m sure they will start noticing something and maybe they will ask questions I don’t really want to answer... 😱 Any advice on how to discretely take opk tests at work? Does anyone of you manage to do it? 🧐