My Fingers Want Me To Chop Them Off

I started taking guitar lessons in December! I have now had three lessons, and have thoroughly enjoyed playing. (Although the fingers on my left hand don't want to play anymore.) Initially, my little brother told me he'd get me started playing, but after teaching me the E scale, he informed me that he'd "rather be doing something else". I happened to mention the conversation between my brother and I to a woman at my church, thinking it was a funny story, and not knowing that she could play guitar herself. Yes, she offered to teach me and I accepted, after my surprised, "You can play?!!" We try to meet once a week, but it hasn't always worked out that way. I don't have a guitar of my own, so I have to use my brother's (which I'm thoroughly grateful for), but it's not the best quality, and it can make even decent players sound bad if their fingers are a tad fatigued.