Balkan trip 1.

Hi All, this is a plan for my very first trip.
I’m arriving from Budapest by train in the morning. I’d spend 3 days in Belgrade (2 nights in a hostel, 3rd night on the train to Bar). (Days 1-3)
4th day in Bar, overnight in Bar, then two days in Kotor and one day in the Durmitors (mounatins), that means 2 nights in Kotor. I’d take a night bus (or train) from Podgorica to Sarajevo if that exists. (Days 4-7)
2 days in Sarajevo and then a one-day-trip with Green Visions (days 8-10). I would like to visit Mostar, Jajce, and I thought we could catch a train from Banja Luka back to Belgrade.

I dont really see how I could arrange the last days, it can be shorter then planned… just I dont know how it would work out.
Do you think this is realistic? Do you have any infos on the sight etc. in italics? Thanks so much!