Parenting teens, losing my mind

[Justwonderedifthisisnormal]

Is it normal to feel like you're losing your mind when you're parenting teens?

I'm letting a lot go, picking my battles and going with the flow (whilst having some boundaries), but inside I'm a mess. DD1 is has just turned 14, DD2 is 8, both are having challenging phases at the moment.

What I wasn't expecting was the knock on effect - total loss of identity, dip in self-confidence, constantly doubting myself, everything I say, how I parent. Feeling like a frumpy ineffective, failing human.
I've read lots and some things have been really helpful. DDs seem okay, doing well at school, nice friends. They're happy but I am miserable! Is this normal?

Maybe put all those books away and just be yourself. You might be feeling miserable because you can't relax and need to perform a role?
They are happy but you are not. How so? What is making you sad?

Thank you for replying User I think that is probably it - I need to put the books down!
Eldest DD isn't with me all the time (shared care) and so I feel under more pressure when she's here as she's not here all the time. DD2 struggles a little with the changing routine. They float around happy, as I say, and I'm scrambling around, constantly worrying about everything. The not relaxing is contributing massively.

I'm really not sure what is making me feel sad. It could be anything, menopause, tiredness (DD2 and dog don't let us get much sleep at the moment), family dynamics. I'm not normally consistently sad, so this is new for me.
Just want to stop the world and get off.

Include a relaxing moment when you can with or without the kids. Baking a cake together or you having a bath with a nice book and a shockingly expensive bath product. Walk the dog together making silly jokes about the people you see walking around (that man is rushing home because he thinks he put the cat in the dryer or other silly innocent nonsense) .
Life is good and sweet, live in the moment, putting social media away for a bit, and if you struggle with the routine, create a chart with the girls, stickers and glitter and make it a family goal to smoothen things. Voice your issue, for example laundry piling up, and ask girls what they suggest and they might take some of the load away. New baskets, a laundry hour at 7 pm, ..
Don't overthink it. Be you, enjoy them.