It must be very difficult for you and your yorkie with you working full time. Have you any family that could help? I work and so does my hubby but we seem to work opposite shifts so Pip is never left alone for too long.
At two years old he is like a clockwork yorkie! I take him out in the morning and he always does two poos, funny I never count his wees but he does wee too. He is then taken out by myself or Bob during the day and last thing at night before bed. If I go out the first thing I do on returning home is take pip out for a wee.
When I am out he is left in a crate that is 3 feet by two and there is enough room for his bed water and food bowls and newspaper on the base just incase he needs to go but this has never happened as yet.
I hope you can get into a routine. I am sure you will get lots of good advice from people on this forum I know that I have.