I know you have lots on your mind and tons of things you want to accomplish, but it's okay to slow down and live in the moment. You have plenty of time ahead of you.
Speaking of living in the moment, that's especially true when it comes to your kids. They'll be teenagers and young adults before you know it. This time with them is so precious.
Be content with where you are in life right now.
You know how you said you'd tell your 16-year-old self that it doesn't matter what other people think, it's okay to be herself, and her value comes from God and not her accomplishments? That's something you still need to remember sometimes. ;-)
Oh, and you know how you feel kind of weird about approaching 30? Just wait 'til you're approaching 40 and your oldest son is almost 18...
There are some things you want desperately that you just can't have. You're causing yourself unnecessary pain by entertaining those ideas.
If it will cost you your self-respect or integrity, don't do it. It's not worth it.
Start reading the books on your shelf that will prepare you for becoming a doula and a childbirth educator. Not being able to pay for the programs right now doesn't mean you can't get started on the reading. You'll be glad you did.
Stop putting so much pressure on yourself to be perfect. It's not possible. Do what you can do, and give yourself grace.
Don't idealize other people and strive to be like them. God made you to be like you, with your personality, your likes and dislikes, your passions, your beliefs, and your circumstances. Remember that quote you love: "It is better to live your own destiny imperfectly than to live an imitation of somebody else's life with perfection."