I can understand where the OP is coming from.
I'm a bit older (31) but in a very similar situation. I've known my bf for about 2 1/2 years, and we've been together for 1 1/2 years. We've spent hours on IM or video chats for nearly every day since we met, and have had 3 visits of about 6 weeks, cumulatively.
In the 'normal' course of events, if we lived in the same country, we'd have moved in together a while ago. And that would probably have been it. I'm not really into the whole Bridezilla thing, and he's somewhat ideologically opposed to marriage, so we'd have been perfectly happy spending the next 50 years in an unofficial union.
But this isn't the usual relationship, and we don't have that option. If we want to be together permanently, we have almost no option other than to marry. We've decided to go ahead and tie the proverbial knot when he visits in November.
Are we rushing things? Sometimes it feels that way. I know I'd be less nervous if we'd had the chance to live together (or even in the same postcode) for a while. But some things in life require a leap of faith, and that's what this is.
Will it work out? I certainly hope so, and I'm 97% certain we'll live happily ever after. I know that the process of adjusting to life abroad might put additional strain on our relationship. I also realize that, if it doesn't, the immigration issues will complicate things.
But on the other hand, I know that spending another year, or another 5 years, doing the long-distance thing isn't going to change any of that. It isn't going to magically make us more compatible, or let us know each other any better than we already do. All it does is waste time that we could be spending together. And we're just not willing to waste more time.
Realistically, when you're in this international-relationship situation, marriage
is, ultimately, the only way to give the relationship a shot. It's not necessarily fair, and it does make things harder, but it's reality.
So, that said, I've had similar concerns about dealing with my family. Basically, I've been saying for a while that 'someday' I planned to move there to live with him. I just said that the timeline was undetermined, because of the immigration issue. When we finally decided to go ahead with this, I wasn't sure how/when to tell my family.
My boyfriend and I aren't doing things quite as non-traditionally. I'm getting a ring (silver & CZ - I also abhor diamonds), so there will be an 'official' engagement. But beyond that, our plans are still very uncertain. I thought about waiting until we had all the details ironed out before springing this on our families, but it would have left very short notice, and there were some practical considerations. Also, I was too excited.
The problem has been that, the more family members we've told, the more complicated it's gotten. We want something very small and very low-key, but other people jump in with their own expectations about the event (my sister's best friend wants to come, his mother wants to buy a hat, etc.), and so it's getting messier. I know it'll all work out, though possibly not without stepping on a few toes. Luckily, we're ok with that.
If I had it to do over again, I think I'd wait until we knew exactly what/how we were going to do things. However, I do think I'd tell them before we actually got married. When I told my dad we were going to do this, he asked 'How come?' And then ranted to my sister about all his children abandoning him. I don't even want to think about his reaction if we'd just shown up already married! Especially as it'll be during deer season. There might have been a tragic hunting accident.