Itinerary help - Trieste to Ljubljana?

My boyfriend and I are planning a graduation trip for September (I'm graduating uni wooo)

We have maximum 10 days we were gonna start in Trieste, spend a few days there (I really wanna see the skocjan caves), then spend the majority of the trip Ljubljana (bus there is about 20euro) doing day trips (lake bled, soca river).

Whats the best way to divide our time/does anyone have any other recommendations for day trips/where to stay? We're trying to keep the cost lowish but we can splurge a little.