Croatia + Slovenia backpacking recommendations

I am looking at doing a solo travel backpacking trip through Croatia and Slovenia. I already have a bit of an itinerary sketched out in my head, but would love to hear what others recommend! Roughly three weeks long, looking at going late August/early September. I AM a young adult female, if that makes any difference in comfort levels of safety at any locations, though I have heard these areas are pretty good.

Some of my preferences: - Costs on the cheaper side - Not a huge foodie, so dining experiences are VERY low on my list - Looking for a friendly social atmosphere, NOT looking for a party/clubbing atmosphere - Would love to hear hiking/outdoorsy recommendations, but I do already have a bunch of these on my list - Potential plan is to work south to north - Really love experiencing nice swimming and beaches, but want to stay away from the packed beaches as much as possible - Interested in semi-touristy creative based activities, looking at art teachings in Rovinj for example - ^ Similar to above, physical activities. Really want to try out new things as much as possible. I'm fairly physically fit/athletic - Architecture + nature + culture are the big ones for me. History is good, but I'm not HUGE museum/tour buff - Long lines are a hard no for me. I am willing to get up early to avoid them if possible though - I'm fine with less than modern/top-of-the-line services ans experiences - Biggest thing is wanting to explore local culture as much as possible + seeing the less common things!

Happy to answer any other questions!

Where would you recommend going? Any specific itineraries? Activities you'd recommend?