Rogersa, I feel for you! Been following your thread every now and then... It feels like such a big decision! I always knew I wanted a solitaire so that really narrowed things down a lot for me but there are so many beautiful designs out there!
It's funny, I'm obviously from my postings FULLY involved in the decision re: my "ugrade" (doing and enjoying all the research - it's a very pleasant distraction from work and pregnancy pains!)... but all of this designing one's original ring stuff seems so foreign to me! Not to say it's not uncommon these days - my sister in law was there at every step of her custom made ring and that's fine - but it's kind of romantic to let him choose too! My brother, I think, did it PERFECTLY - he took her out to Birks and Tiffany's and a few places one day and asked her to show him the one style she loved the most... then he (with my help!

) took it from there and she was not disappointed!

He ended up at Tiffany's and was thrilled with his choice ... they spent under $10K and she has a stunning embrace ring, and hey - one day 10 years down the road she always has the option to upgrade there to any style/size she wants! I know right now she can't even imagine doing that but the option is always there, right?
I guess what I'm saying too... is that I never ever thought I'd upgrade or change my setting but both me and my sister did and we've both married for less than 10 years (so not that long even)... I lost my original one, she tired of the rather modern setting he chose... the point is, I don't think you should put TOO much pressure on this ring being perfect as you never know, you might upgrade down the road, or it could be lost or stolen, or even tire of the halo? 2-3 carat solitaires are MONSTER rings for newly engaged young couples aren't they? I mean WOW - 3 carats?! I still don't know anyone who has one like that, even wives of CEO's! I mean if you can swing it, go for it! And only you and BF know for sure if you're comfortable with that. That's definitely not our business... my point is maybe you're making this too hard on both of you. Maybe it's not totally necessary to get THE RING right now? You could always upgrade to your dream ring in 10 years and take some of the pressure off of feeling like it has to be absolutely perfect/as big as you'll ever want it to be?
It sounds like whatever you do you're going to end up with one gorgeous ring! I'd just hate for all the romance to go out of it with all the stress! And it's true if it is financially stressful it's not good - you never want to look at it as a sign of something negative, only positive... even if it's "only" 1 carat right now, KWIM?
Good luck!