Congratulations Sweetcell and Manimtired! And you're welcome for giving you an in to announce your engagements :p
My sister will be 20 in December, her boyfriend (now fiancee) of 4 years is a bit younger. Neither of them have ever dated anyone else. They work well together and you can tell they care very much for each other, and I'm sure they'll do fine. I've always known they'd get engaged, but I was expecting them to wait til they graduated. (They don't live together.) I wasn't particularly happy with this news because yes, they are very young, and very naive. My view is: what's the point? Why not wait? Why not have your own life for a little while, graduate, figure out your career path? If you love each other, what's the rush? It was doubly as worrying because they are both in college, and I have a cousin who is a couple months younger than me who got married last year at 20. She would have graduated this Spring, but she got pregnant.
However I shan't judge, it's just frustrating is all. I am biased against marriage in general, and have gone on tirades against young marriages before, so I'm sure there are people out there with smug smiles on their faces in my direction. Oh well. I shall be content to be Ye Olde Maide. I don't have much faith in the institution in general.