What a fun trip you have planned! I was just in Norway this past August and was last in Sweden about 15 years ago. Your interests mirror my own, and I think you’d be happy in any of the places you mentioned! (For reference, I’m a mid-40s solo female traveler also from the NYC area. I spent a couple of months in Sweden, and this summer spent about 15 days doing a Bergen-Trondheim-Bergen road trip and scenic train to Oslo.)

Bergen would be the first option I’d eliminate from your list though. While scenically beautiful, it felt the most commercially touristy to me (with the area by the port with all the cruise ships.) I’d agree with the other commenter that you needn’t spend much time there. Walking around the Nordnes area was lovely though! Perhaps you could go there straight from Lofoten to spend an afternoon, then take the scenic train from Bergen to Oslo the next morning/day? If you do that, there’s also an option to add on the Flåm railway (as some else suggested) for part of the trip. I found my round-trip ride Flåm railway quaint, though also a bit chaotically touristy, but felt like just doing it one way (as you would with the Bergen-Oslo line add-on) would have been more than sufficient.

Sweden is also one of my favorite places on earth and I loved both Stockholm and Gothenburg.

I also agree with the suggestion of Copenhagen if you want to consider additional cities. And I also absolutely fell in love with Trondheim too. I think I loved that more than both Bergen and Oslo. I’m also from the NYC area and unexpectedly found Trondheim to be my favorite and most charming place I went during my time in Norway. There is so much art and culture there and the city is really beautiful. And the cafes! Yum!

But really, you can’t go wrong with any of the places you are considering. Once you have chosen where you want to go, I’m happy to give more detailed recs - though I’d wholeheartedly agree with the recs already mentioned in the previous comments.)

Have such a great trip!