Wow so sorry for your loss. I must say that 50lb is an amazing accomplishment and she is smiling down at you encouraging you every step of the way. Keep it up sweetie, and of course you can always talk to her.
I am really sorry for your loss. I lost my mom in May, she was only 50 years old and my best friend. It is so hard to not be able to tell her how good I am doing, she was always my biggest supporter. I do feel that she is rooting for me up above, and I'm sure your sister is doing the same! Keep going strong, I am sure she is super proud of you!