parenting...

I'm going through a spell where I feel like the worst mother on the planet. Well, I know there are some worse, but I'm not being the mother I envisioned myself to be. It's all roses with Elise, but she's a baby that just coos and laughs and looks cute. The challenge is really with Lola...she has learned a thing or 3 from life, preschool, us, etc....She is growing up and testing her boundaries with me, which is perfectly normal. But it shakes me out of my comfort zone and my patience becomes tissue-thin. Gone is the little smiling toddler who just aimed to please...she has been replaced with a stubborn miniature adult who thinks for herself (yay!) and has learned (somewhat) the "virtues" of deception ("I DIDN'T DO ANYTHING!" is the immediate response to her name being called), an angel with just the hint of the teeniest, tiniest little devil horns peeking out of her golden halo of curls.
When 5 pm rolls around and Lola has asked me the 1000th question of the day, never leaving me alone for 5 seconds, the baby is crying and clinging to my pantleg as I attempt to muster dinner together, Lola is the one who receives the bunt of my frustration. It's so unfair to her and it fills me with such guilt. Later on, I see her sleeping in bed and I'm so incredibly remorseful. I used to campaign on and on about how I will never be to my daughters how my mother was to me, but then in the heat of the day, I embody my mother. I wonder how much of it is personality, genetic or otherwise. I thought my mother and I had no personality in common until I also became a mom.
I struggle with this off and on...maybe it's hormonal but I know my patience lacks severely when I've had anything less than 7 hours sleep. Some days are great and maybe there's a pattern to recognize there. I really don't want Lola to grow up being as insecure as I was (am still!). I really believe it begins here at home. Anyone else out there struggling with something similar?
I LOVE her personality, I really do. I love everything about her that IS challenging. It's just that it's so....well....darn challenging!