Much better. I corrected slightly the third panel, というわけで is more or less an idiom, and rarely is it correct to translate it as "saying that".
St... op...Kya!I am, y'know,
I am, y'know,My little sister is so cute and has become such a good girl.Aa...so very happy.Uh, Nee-san? You're... you're scaring me...
Nee-san = Big sisterWha, what are you saying...So you see, today you and me are going to sleep together!