Hi there
I'd be a little more proactive than just seeing a physio - I'd be considering a new paediatrician if I were receiving advice like that. My interpretation of what your paediatrician said may be awry, but it's my understanding that he was saying if the physiotherapist can't address the underlying pathology, then seeing one is a waste of time?? If that were so, then most of my career has been a waste of time! Ouch!!
I do agree with wutti that an appointment with a paediatric physio is a great idea at this stage and I don't think that another month or so with no therapy is going to be worth getting worried about. However, it is my understanding that if a kid has low tone that any positive alterations to that tone brought about by physiotherapy will be transient at best.
Now, you did mention about your child's motivation and ability to walk with hands held, but I would like to ask does she do any independent standing at all? Either with couch support or without. And, is she cruising yet?? (ie, sideways walking around the furniture)