How do women get married with only one ring? Especially when they don't like common wedding rings?

She and I both want to get married. I have not proposed yet. I was working on a design for a custom engagement and wedding band combo (two parts, engagement and wedding, that when put together would make one awesome ring). I finally got her into a jewelry store (Keepsake) for a sizing and to get an idea of her tastes. Now I don't know what to do. She didn't like a single ring in there. She gravitated to the plain band (was it for a guy or a girl? who knows) and tried those on. Later she said she didn't even like the bands because those are too plain for her, but every thing else was too much. She tells me she doesn't like diamonds. Fine with me. Money doesn't matter either way, just her being happy so I'll have bonus cash for the honeymoon right! 1-what kind of ring can I get her that's more detailed than a wedding band and less detailed than every other common wedding ring? What really got me confused is she says she'll only wear one ring! I'm totally lost on that one. I though all women got two rings. 2-My main question is how does that work with two events, engagement and wedding, but only one ring? 3-How can I possibly propose with out a ring or get married without one? 4-Also, are some rings supposed to be on the right hand sometimes? Unfortunately, I'm not going to buy a ring, have a custom one made, or even propose until I can figure out the logistics. We get to wait because we have unique tastes I guess. Can you please help me with the above four questions? Thank you for your responses.