Curiosity killed the pussy. So to speak.

Well, yeast infections certainly suck, but as far as "STIs" go (it seems they're not technically considered STIs), that's about as mild and mundane as it gets. I'd say you should rather be glad you had a great time with someone you like and got to learn more about your sexuality and yourself. I don't think that should qualify as a red flag for your partner, since she might either not have known she had one, or not have known it was transmissible through sex, and it shouldn't prevent you from trying something more long-term with her, provided that is what you both want, obviously.

Speaking from experience: if she does not have an infection, herself, just some general rules of thumb when with women: WASH HANDS!! this is the one thing that will get me right off. If fingers are down there, wash them first with antibacterial soap and rinse well. For a little extra, use rubber, vinyl or nitrile gloves. That helps prevent getting anything under nails or scratching inside. If cunnilingual actively is involved, brush teeth and tongue and swish/rinse with plenty of water if going bare, dental dams are an excellent barrier but I understand they can be uncomfortable/difficult to use. But above all, communicate so you both can stay clear of infections like this. And no, it's not considered an STI because it's incredibly easy to upset our natural flora balances inside. Good luck and welcome to the bi club!! =)