@ysette9 - you are legitimately in a really hard life phase. The logistics become different (driving, activities, emotional parenting of older kids, etc), but you are deep into the hardest physical parts of parenting + kids getting sick all of the time + lack of sleep, etc. That part, I promise, does get easier!
We've definitely had years that are about keeping it together. For me, in those years, I try to choose a few very small things I can do to make life more manageable. Making journaling a daily habit, meditating more often, turning 3 meetings a week into walking meetings, riding your bike to work is awesome (you are inspiring me!) Maybe 2019 can be the year of small positive steps?