Congratulations on making that first catch! I remember when I caught my first baby as a primary -- I couldn't stop thinking about it for days! Every baby since has been just as exhilarating as well.
I have never been in midwifery school -- I am finishing up an apprenticeship and have done self-study, but the one thing I have to say about working as a midwife vs. working as a student/apprentice is that you have a greater degree of control over your own schedule and your own workload. I know midwives who provide care for 80 moms and babies a year and I know midwives who provide care for 8. Once you finish your schooling you will have a lot of choices about how you want to work and you can settle on a model that is right for you and your family. You may even consider partnering up with another midwife and scheduling your most troublesome coverage times as off-call times for yourself (I know I would be happy to work weekdays for example, for a partner who would work weekends).
You and I have kids who are almost identical ages (mine were born 3/00 and 5/04) and so we are probably facing a lot of the same issues re: childcare. PM me if you want to chat in greater depth.
As for right now, I think that what your dh is really saying is that he wants to be able to rely on being able to get to work on time. He sees midwifery as a threat to that and maybe to your family stability as a whole. It is pretty easy to see how he could feel this way-- after all, he doesn't get to experience all of the exhilarating benefits of your work. What would probably help is trying to find more outside support-- family, friends, professional childcare, etc. I have left my youngest with a local SAHM for the last year whenever I had daytime office hours that he couldn't come to (he came to work with me most of the time), hospital visits, and births. I have a list of about 4 other women who dh can call in an emergency, though, and sometimes we have gone all of the way through the list in the morning when I am out to a birth. Sometimes other birth workers can help too. I just babysat for a fellow midwife's daughter today so that she could go to an appointment.
Good luck, and try not to get discouraged. You can always tell us about your exciting births!
Take care,
Stacia