I have a female BP that was hatched mid Sept 2016 (so roughly 5 months old) ... I have seen posts that are making me feel like she could be underweight, but I can't really find a reliable size chart

I weighed her the other day (and it was 2 days after she ate a med. mouse), and she came in at 168g

Does that seem on the low side? Hopefully that's accurate, it's the first time I've used the little scale I got but the bowl was zero'd out before I put her in it so not sure why it wouldnt be

Where should she be? and if she is underweight, how do I help her catch up?