Is is better to fix my teeth now or wait until I'm unmarriageable?

I'm 25 and my adult canines finally came in a while ago, the left one 3 years ago and the right one a few months ago. Of course they came in screwy and crooked. The rest of my teeth are fine except that I have a very slight overbite. My incisors are very straight and bottom teeth are nearly straight with no crowding. I can't really afford braces unless I beg money from my grandfather and he's supporting my grandmother who had Alzheimer's in a nursing home. I've never had a boyfriend before and I don't want to ruin my face while I'm still young and marriageable. The treatment will take 3 years, the time when most young women either marry or start considering marriage. I'm afraid if I wait until I'm 28 that I'll miss my chance of meeting someone. I figure i have about a 30% chance of ever marrying but I just don't look back and think that I missed my chance because of my braces. I'm quite pretty, slim, and I always try to be well dressed and well groomed, I just am not social. I don't like parties, drinking, and I like staying home in the evenings. I have had a few dates, but nothing that amounted to anything.