Possibly stunted growth

Hey all, new here. I just adopted a female corn and she is apparently 3 years old. I weighed her today and she is 135 grams... I'm no expert but I think that is quite small.

I haven't fed her yet(they fed her the day I got her) and I'm researching the size of food that would be best for her. I measured her at 1.5 inches at the widest point and was thinking about the 10-15 gram mice. She doesn't look too underweight as her spine isn't sticking out, but she isn't very long either. I'll measure her if someone wants to know.

Any advice would be nice, her previous owner said they only fed her pinkies, so I'm sure she will love the calcium from the bigger mice, I just don't want to feed her something too big and have her just regurgitate it.