Going through the teen years, you may think things were easier when they were little and you could control circumstances better. Let me tell you, things were not easier when your kids were little, but they were simpler. There's a difference. Hormones and that tension between wanting to be an adult and yet still be a kid at the same time is no joke. It's very complex, not simple. But it's not harder or easier than being a mom operating on no sleep with a baby or screaming toddler. Both stages are tough, but it was simpler when they were young.
When you have adult kids about to move out, you realize how brief the time was that you had them under your care. It's like a drop in the bucket compared to the next 80 or so years they'll be out on their own. Actually, you're in the process of letting them go from the moment they're born. They are God's children. You are just stewarding them for a brief time.
Small children need lots of guiding, correcting, training, and you have a say over what goes on. Then comes the middle part where they have more responsibility, have freedom to go places with friends, test your trust, have different boundaries in place. Then the teenage part where they are bouncing between kid and adult, maneuvering the messy waters of hormones, learning to drive, maybe date, and have way more freedom. The last stage is adulthood, where you let them go to be who God has created them to be. Yes, you are still there for when they ask for advice, you still pray for them, and then you'll move into the role of Gramma.
As a mama, you parent with all of it - emotional, physical, and spiritual. But in the kid stage, it's more physical. The teen stage, it's more emotional. And in the adult stage, it's spiritual. Why? Because now your role is from afar, so all you can do is pray. Prayer is super powerful and trust me, they need it. (This is an excellent resource: The Power of Praying for Adult Children)
This is all the way it's supposed to go, and it's healthy. But as a mama, you MUST learn to let go. You cannot control them. You must lean on Jesus to help you through each stage, and let go a little more in each season. Then it will be easier on your heart when they move out and start their own lives/families.
Yes, you've made mistakes. Nobody's perfect, so don't try to be. Always remember to be humble and apologize to your kids when you need to. Remember to point them to who is really perfect - Jesus.