I've got one about a week behind your girl.
It all sounds normal as Amazing Yorkies has mentioned. With her belly getting fuller as the babies grow, she will not want to eat as much at one time. Try offering her smaller amounts of food/meals several times a day rather than the usual once or twice. My girl is spending almost all of her time in a bed under an end table between our couch & loveseat. I have no doubt she'd have her babies there if I let her............which of course I won't. At 50 days, you still have a way to go; try keeping yourself & your mind busy; is her whelping box ready, do you have all that is needed? How about the quiet space she & her pups will spend their first weeks together? Good luck to you and the mama to be. Keep us posted on her progress.