First wig advice
Hello, and welcome! Your measurements do seem to be on the high end of average on the circumference. If you still have a lot of your own hair, that will make a difference in fit as well. There are many methods to secure your hair, and you will have to see by trial and error what you prefer. I use It Stays or Got2B on my lace fronts, that is it for me. You can also use wig tape which I keep on hand if I need extended hold ( the blue tape). I do not wear wig caps or wigrips. I do not like them personally. Many love the wigrip though. Some women sew clips in at the nape and top for security. I don't as I don't have hair to clip to, and I would be too lazy anyway to do it. If the wig is wefted, you could put bobby pins through for security. If you put your hair in a low pony and pin it up, it acts as an anchor at the nape. Some ladies pull their own hair out along the eartabs and nape. Along the eartabs, it adds to the realism by obscuring the harsh edges. It is good to have a few options for security on hand as different uses might need different solutions. You are getting a ponytail wig? I haven't had one personally, so I don't have particular experience with that type of wig.
There are many Facebook hair groups you can join. I am sorry no one answered you.