I know what you mean about work - Matilda died on a Saturday and I had to go back to work on the Monday and ended up crying in the toilets. Luckily it was just before the August Bank Holiday so a lot of people were on leave and didn't notice. The next year, I lost an aunt and was entitled to time off work, and it seemed ridiculous because I wasn't almost as upset about losing a 90 year-old-aunt who'd had a good long life as I was about Tilly.
It's still not long since you lost Bertie and it WILL feel better in time, I promise. It was months before I could go a day without crying for Tilly. Finally now, I find myself laughing about her sometimes as well as crying. My mum and I were reminscing about pets we've loved and lost the other night, and we laughed about a time when Mum was catsitting while I was at a conference and Tilly really misbehaved
I can remember her with fond memories as well as sadness now. You will feel the same about Bertie one day soon, honestly. In the meantime, you wouldn't be human if you weren't grieving