I would think it would be better to have a goat mated every two years, but it is not essential. You may just have a few issues when you try and get her mated, but not necessarily so. I would have thought that with one milking you will have enough milk for the house and you will be busy with a baby. Have you got someone else who can milk if you are not able? Also your own health may take some time to recover ( for example after C-section), so if you don't have anyone covering it may be wise to dry both off for next spring and see how it goes.
I wasn't able to do anything even slightly strenuous esp after baby No 2 (both mine were C-section) for a few months...