Juggling Life

I been struggling to find a balance in my life. I have a hard time prioritizing, scheduling and managing my time and following through when I do plan things. There are tons of resources out there and I've explored alot of them. But creating new patterns/habits is a hard thing!
My summer bible study group is going through the book Boundaries. I know I need it! I do have a hard time knowing when to say yes and when to say no. It sounds like such a simple thing but its not! Because when you get down to it its about your relationships and we all know those are never simple! I'm often worrying about hurting people's feelings, letting someone down, etc. So then I commit to something that I may not really want to be doing - sometimes maybe when I should be doing something else. Then I'm frustrated the whole time wishing I'd had the confidence to say no when I wanted to. But I want everyone to feel they can count on me. So I often feel obligated to help when asked.
Then sometimes, after I've said yes over and over again, I get overwhelmed and burnt out. And I start saying no to everything because I'm just so tired of saying yes. I know - I'm weird. Its a vicious cycle. It shouldn't be this hard to find a normal balance in life. Should it? I kind of miss the structure of when I was younger. I had school, chores, free time... and it was sooo much easier then. No "real" responsibilities - you know, like caring for a home, a husband and being primary caregiver to two boys, one of whom has special needs.
There needs to be a young wife and mother training course. I'm talking an intense bootcamp that drills the basics into you so when you get home you know exactly how to manage your time, money, home, kids, husband, social calendar.... everything. Maybe then I'd feel like I knew what I was doing. Am I the only one who would go for training like that?