Lack of protein?

[raviolli]

Hey all...im new so still gettin the hang of this forum...but i have a question which is what brought me to become a member in the first place. I've had my BP for a month next Tuesday. I got her from Petco (at least i think its a her) she was the only one left. Anyways, she seems to have poor muscle tone. Shes got sort of a raised backbone and a not so round shape...more triangular. It wasn't so bad when i got her, but i notice it more now. It's not that its getting worse, just that im noticing more. She's very calm and loves to be held. Theres no problems at all feeding, even the first time (got her on a Saturday and i feed every Wednesday). Could it be a lack of protein? The first week i put a second frozen fuzzy in just to see if she'd eat 2 each week and she turned it down however I noticed this past thursday when she came out she was acting hungry. im thinking i might try 2 next week. But also, the more i notice, the more i worry. She has had a pink belly for at least a week now, i figured its almost time to shed so ive been watching her eyes. nothing yet, but shes still pink. and shes not as active as she was the first week. she'll come out at night for an hour or two, but then go back to sleep for the rest of the night. the first week she'd be out the whole night (or at least til i fell asleep, which wouldve been pretty late about a month ago).
any info would be appreciated
thanks