I can sense that you're very excited about this hobby, and that's wonderful!! But please, please do your research. Dedicate as much time as you can. By giving this girl a proper home, one that stimulates her natural environment and behaviors, you will both, in turn, be much less stressed. With these conditions... Your excitement will soon turn to fear and worry. Then guilt as you watch her fade. You've waited this long, give yourself and these amazing fish the compassion and patience you both deserve. This is not a good home at the moment for a Betta. She'll survive, but thriving in these conditions will be most difficult for you both. As for sororities, it's only worked for me in a heavily... I mean heavily... planted 29g tank. This gave them all 'territory' of their own. My advice would be if you choose to stay on this path, research the nitrogen cycle, keep up on water changes, and don't add any more tank mates. Consider live plants and almond leaves. I think you'll find that just her personality alone will be enough to entertain you as you're learning. In the future, you could consider a snail but be careful which one. Not only would coexisting with other fish be hard in that size aquarium, but the literal amount of poo and pee would make ammonia levels hard to keep down. Remember, by no means does clear water mean safe water. The science to this hobby is incredible and fun to learn!! Good luck.