Ouch, I'm sorry! I'm in the same boat, so I totally understand - fell and broke my foot 3 weeks and 1 day before our flight out to DLR with a 2 year old and 4 year old. I have been planning this trip for so long and I think I was more excited than our kids, so it's hard not to feel frustrated and disappointed. Luckily the grandparents on both sides are going with us, but it's going to make the trip a challenge for sure.
I've never used an ECV before, but it sounds like with your situation with only one other adult, that's probably going to be the best option. I saw Deckert's and OC Medical recommended on another thread, and I'm sure there are others. If you're flying, I think airlines have wheelchairs you can use at the airport, and you should be able to preboard your flights, though I'm not sure if they allow more than one person to preboard with you.
Our trip is in just over a week and a half and I'm still working out the logistics myself, so I can't offer any other advice on that front. But if the doctor puts you on crutches, I would really recommend getting crutch pads! The gel kind offer much better support, especially on the hand grips, and it makes using them so much more bearable. I found some on
Amazon called Crutcheez (I think), and it includes both hand grip and armpit pad gel covers.
Maybe you'll luck out and it's just bruised or a mild sprain, and it will feel better after a few days of rest?