I had a ring picked out that I wanted, and even had the pic of it on the fridge so that it was there for him to see when it was time to buy the ring. We ended up getting engaged, but since I was off work at the time (had my son) the $$ was tight, so he got me a birthstone ring as a temp ring. We were engaged last Oct and I got my ring in June I believe. I don't think it is weird to get your ring later on at all. The ring I got was not the ring I wanted either, but he knew that I didn't want a big ring that stood above my finger too much, or I couldn't wear it to work. When he looked at the ring I wanted, it did stand up a lot, so he picked one out, and I love it!!!!
I say talk to him about it, and if you decide to have one ring, then there is nothing wrong with that either. A lot of people are only having one ring and whether you use an ering as your wedding ring as well, or you just get the wedding ring, all that matters is the love that the 2 of you share.