A lot of your worries seem to be more paranoia based, more so than OCD.

It's also pretty natural for a parent to wonder if they are a good parent or not.

The mental health workers aren't the same people as who would be able to decide if you were a fit parent or not. There would be different workers who work for CPS who make that decision, although the mental health workers may make the request for an investigation if they think that you are a danger or an unfit parent. But they didn't make the decision to take your kids away.

CPS wouldn't take your children away without having cause. Sometimes the reason for the removal is something that is temporary, other times it is more permament. It doesn't mean that CPS thinks the parent doesn't love their child, just that they aren't capable of taking care of the child at that time.

When it comes to custody between parents, the court decides. It's a judge's decision who to give custody to, and how much. They are given testimonials and what not from professionals if there are any involved (such as your mental health workers), from people involved, and the parents. Especially if there is a dispute. But it is the judge who decides who gets custody, NOT your mental health workers.