If I could give you one piece of life advice, it would be to stop planning your life. While that may seem like an unproductive suggestion, you need to do it. Micro-managing your own life is not the best strategy to being successful. As someone who has been a long time planner, I can confidently say that planning less has led to being happier and less overwhelmed.
So let me rephrase my argument here: Plan strategically, not constantly. Yes, you cannot just stop planning your entire life altogether. That is simply not feasible or smart. A better option here is to plan when you need to. Keep track of important due dates and important events, but don't let your schedule take over your life.
There's a difference between cluttering your mind with an endless to-do list and having the to-do list exist on paper. A way to be strategic about this is to only plan when you need to. Yes, you need to plan accordingly for a big project or paper that's due soon, BUT you do not need to plan every minute of your day in order to be productive. It's all about balance.
The best way to stop planning is to take life day by day. I don't mean this in a cliche simplistic way. I mean truly living each day presently. Each day is a unique and brand new opportunity to essentially work toward your goals. Having a plan for the day and just that day is the key to this strategy.
As someone who easily gets overwhelmed, being able to have less to worry about is super helpful. Obviously, I still have a lot to do, but I don't let it be a constant worry. I have also noticed myself being happier and more content with myself.
So basically, if you get easily overwhelmed by all your responsibilities, try to plan less and just enjoy life. It will take time for this to work, but the benefits are amazing.