Wow. Thank you so much for the wonderful comment. We're very touched!
As for Steam, we're not exactly sure if you can. You will have to check and find out. Sorry. One thing's for sure though. You will have to obtain the Achievements again. QvQ
Ah, I managed to transfer my save files! All I needed to do was copy the compressed zip folder that I installed from itch.io and then paste it to the Steam file. Now I can continue my previous save. Just posting in case anyone else is wondering if it's possible - it is :) Also, I didn't have to obtain my achievements again. As soon as I pasted the folder and it finished extracting, my achievements were credited :) Yay!