I LOVE the mare, she is all kinds of cute, good solid, reliable looking, how does she ride? Is she comfortable at all of her paces? I had a big draft cross mare here who was just rocking chair smooth in every gait, so loved riding her.
As to breeding her, well as everyone else says, think long and hard about it, I totally 100% understand wanting to have a little bit of your mare, just remember you are risking her life in that pursuit. Maybe it's just me, I had a small registered breeding herd here, but it was when I was waiting for my heart mare to foal, I decided to quit. The worry that I had over that mare and the thought of losing her made me seriously question breeding anything.
I went out and bought a daughter of hers that was already on the ground, so now I have 2 of her daughters, one bred and one purchased and I love them both, neither of them are like their mother, I don't feel like they are a bit of her, they are individuals in their own right.
Will I breed again, maybe, I wont rule it in or out, but when and if I do it will be breeding like with like. I have yet another mare, who is to fine, I would love to have her, only heavier, and for a millisecond thought about crossing her with a heavier stud, LOL then I remembered the worry and the cost and the risk and decided against it. The odds of winning that particular lottery are slim, so no way that one is happening.
You say the foal will stay with you for ever, sorry you can't promise that.
You want a lighter foal, can't promise that, as other have said you could get frankenhorse.
IF you are dead set on breeding her, then think about what you really want as an end result, and think about marketability, and then choose a stud for all the right reasons.