You're definitely juggling a lot of challenges all at once. From one mum to another, my heart goes out to you.
Sometimes we're conditioned to feel guilty through that thing we can often hear, growing up, 'There are others who have it worse than you. Think about them and stop feeling so sorry for yourself'. I think when people say this, they can be dismissing our struggle. We should look at our struggle based on our experience. Even for a little kid who's facing the grief of having lost his teddy bear, his best friend, if that's 1st time grief for him it's serious grief. It's our ability to feel our struggle/challenge that makes it so intense, no matter the circumstances.
Although my babies have grown a little (daughter 19 this month and son 16), I recall some of the psychological torture in the early years. It's kinda like the powers that be say 'Okay, I'm going to give you a crash course in bringing out the best in you; here's a baby'. Then you graduate to more difficult challenges that push you to amazingness - 'Here you go, here's a second. Juggle that one sister! Let's see how you go. By the way, I've ramped up the volume on guilt. You'll feel it far more easily now'. Yep, thanks for that :)
For a start, you've grown 2 human beings inside you which definitely makes you pretty amazing. You gotta admit, that's really quite incredible, to grow people. After this point, I'd have to say it becomes a mutual thing. Your kids start to grow you, develop you into a whole new person. They'll develop your patience, your ability to manage challenges/stress, to manage and introduce more outside the square thinking, to manage time etc etc. This is mind altering stuff. Feeling the challenges is one of the things that makes you a sensitive mum. Oh yeah, let's throw in some serious sleep deprivation just to add to the sense of torture. No one really talks much about the torturous aspects of motherhood. I experienced PND with both my babies.
Not sure how old your eldest is but do you think they'd vibe high through being given the status of 'Legend of the household' (LOTH). LOTH collects the washing to be done, does some vacuuming, dusting, bed making etc. Without them, the house falls apart :) Even if they're 2 or 3, they can push a vacuum around. Explaining to them how incredibly important this role is, is a self esteem booster, especially if they're feeling unimportant with a new baby in the house. LOTH is also a role involving skill development.