Hi There
It is hard not to worry esp if the nurse told you to get it checked out.
My DS1 didnt crawl til 13 months... i knew he would be late bc both my DH and I were but i still did worry. My MACH nurse hadnt told me to see anyone, but I was thinking of going to a physio in case. He did it in his own time. I dont think 12 months is really an age to worry too much - esp if she is sitting, rolling etc and meeting other milestones... plenty of kids dont crawl til way after that... i think the issue with crawling and walking is that they are the milestons ppl focus on bc they can see. is she happy? does she clap? babble? etc etc. i am sure she is developing in lotsof other ways.
That said, it cant hurt to hace her checked out for your peace of m,ind - if there is sonmething they can do to help her, better to start earlier than later (and you will now worry eiother way bc a seed has been sewn in your mind).
Bets of luck to you!