traveling at 17 alone abroad, your pov

hey!

i dont really have anyone to travel with abroad. i have saved up some money and i would like to travel around europe. the countries i am interested in are italy, poland, slovenia, romania, spain, portugal. yes, kinda random:) i want to travel on a budget and i am fine with sleeping in buses/trains overnigh whilst getting to another country (not every single night obviously haha). i would probably visit most of these countries one at a time, not all at once. how safe is this for a female traveling alone at 17? i heard i cannot check into a hotel on my own, if thats so, what are my options? should i just wait another year and save up even more? otherwise, im more on the muscular side, so im not a tiny underweight girlie. ive traveled alone with my sister to USA, ive traveled to switzerland, norway, slovakia, czechia, england and multiple times with my fam to usa. i have flown 10+ times in my life. any things i should prepare myself for solo traveling? i would read up on laws in terms of self defense etc. before leaving and based on that i would have a pepper spray/ at least deodorant for defense. i also took self defense classes in the past, and boxing. thank you for any insight!!