My girls are still in high school, but I worry about this, too. I had such a horrible childhood, I tried to do everything I could to protect them from bad things. I think I over did it to compensate for the fact that I didn't have a mom growing up. Now I am worried I didn't raise them strong enough. We all make fun of helicopter parents, but a lot of us are exactly that. Well, I am and I admit it. I wish I had done things differently.
Don't know if this will ease your mind or not, but maybe it will.

My parents were helicopter parents, long before there was a catchy title for it. In fact, I dare say they would put most "helicopter parents" of today, to shame. They shielded, censored, protected, guided, shadowed, followed, and watched us. All of the time.
There were three of us daughters. Many of their friends warned them- "You are way too involved!", "Your girls need independence!", "One day, you'll see- your girls are gonna be so tired of having you in their business, that they are going to rebel and do the exact opposite of what you are teaching them!".
Those friends were wrong. All three of us finished school, went to college, got married, have/held jobs, had children (to which, we are all proud Helicopter Moms). No scuffs. No scrapes. No major rebellions. Not a one of us folded under the 'pressure' of a world without Mom and Dad being only two minutes away. We knew they were always a phone call away if we needed them. But, more often than not, we knew we could do it without *having* to make that phone call. Their protection showed love, which gave us the confidence we needed in ourselves.
I get angry with news reports that showcase the few kids who have issues that lead to tragedy, and then point to the source of those issues as being "over-protective" parents. Our
job as parents is to protect! We've been down the road before, so we know what's coming for them. We're supposed to be there to guide them, teach them, and keep them safe until they can do it all on their own.
Sounds like you are an excellent mom, to me. Don't worry if you've hovered too much, I've no doubt that one day your children will be thankful that you did.