Back to work feeding advice!

My little one has just turned 5 months old, and I start back to work next week. Tuesday - Thursday 2 - 6pm (12hr p/w).

I am sooo confused of what to do for feeding because she is breastfed and feeds at random times during the day, sometimes only an hour between feeds sometimes three hours.

She gets a bottle at bedtime (7:15) this is mostly breastmilk but if I haven't expressed enough, it's formula.

I currently only express once in the evening to fill her bottle for the next night.

Are you back to work, what do you do? I'm keen to breastfeed until 8-9 months but worried it won't be possible.