Need advice about germs and illnesses

Ok so I have OCD and I feel it is manifesting itself into a fear of illnesses for my kids, and I need some advice on what every one else is doing regarding germs. I have a 2 year old and a 3 month old. Both stay home with me. Last summer I started taking my son to parks and play dates (while pregnant) and we were sick every week it seemed like. Now that I have a new baby I have been keeping him in until the last few weeks when weather improved and we’re now on our second cold. (Ugh!) so many viruses scare me, especially with the new baby not being fully vaxed yet. Do you still go out with your older kids? Do your older kids bring illnesses home from daycare? Is it better to let them be exposed now (even at 3-4 months) or is it better to protect them? I find myself constantly sanitizing my 2 year olds hands and feeling nervous constantly out.