sounds like your samatha is going well, but needs a little more support from you. Would it be possible to do 10-15 min samadhi 'top ups' without feeling obliged to do an hour or more during weekdays? I know some people who have been helped using this method.
You could also try just focusing on an entire breath for just on breath any time you can do it. A little 'samatha break' if you like. All these add up.