This sounds roughly normal for what I came to expect back when I worked in an office with many people who had school-age kids. I had a colleague who wryly referred to his kids as "my little plague carriers".

When I stopped working in an office, I almost completely stopped getting sick.

+1 for office work as disease source. Plus taking public transport (mostly underground trains). Today I avoid the subway almost completely, taking my bike almost everywhere, to avoid getting sick during winter. (No kids though)