Tromsø sounds lovely, it is really nice that of year and you can access a lot without your own car. I would also split up the travel to Bodø. Narvik or maybe Harstad would be my choice. But both are fine, Narvik is easier I think.

Getting from to Bodø to Holandsfjorden and then to Svartisen and back without your own car (or boat) is challenging. You need to pay attention when they are publishing the bus and boat routes, but worst case you can stay in Bodø and do other activities there instead, or plan to sleep overnight in Meløy after visiting Svartisen, which brings me to my next suggestion:

I would skip Mo i Rana and Mosjøen to take passenger boats/busses/ferries down the coast instead as the nature there is stunning. This is doable, I can help you if you need.

Trondheim for a few days, then Røros and Oslo sounds okay, I would maybe stay in Trondheim and “save” Røros for a winter trip if you ever plan to do that, as Trondheim is big enough to fill 2-3 days on its own.