“Badly miscalculated” sounds weird at first, I get it! It’s not really a double negative, just style. If you want super clear, “severely miscalculated” works. Also, this guide on research proposals https://samedaypapers.com/research-proposal/ gave me some neat tips on phrasing tricky sentences without confusing anyone. Totally useful for writing sharper stuff.

You should use "my" instead of "mine" in this sentence. So, it would be: "I so appreciate you taking my and Gregg’s child to school today." "My" works better here since you're talking about the child in a shared context. "Mine" is used when something stands alone, like "This book is mine."