I am 5' 6" and 118 lbs. Is 450cc a large size for my frame - would it significantly negatively affect me, back pain, etc.?

I am 5 foot 6 and about 118 lbs. I have some muskuloskeletal issues including hypermobility. I noticed some more low back pain years ago after getting implants. But I had also been doing some physical physical therapy that was not going very well at the time. I eventually had them replaced over the muscle and went down to 450 ccs high profile which puts me at a c cup. I was originally a very small breasted woman, had three three kids, went up and down sizes as I breast fed, and was left with not much tissue at all. Hence the implants. The 450s ruptured after only five years. Therefore I will be replacing them. I am considering going down to 350s in hopes that it will help with my body. I have always had flaring ribs and after my pregnancies also have a tilted pelvis. I did have these issues before my implants. I did struggle with all of these things before. Neck pain due to my core and ribs and main muscle groups not working together. When I ask pts their opinion about the size they all tell me it otis a personal preference and it was not th cause of my problems. Might help..might not. My question question is: is 450 a large size for my frame in that it would significantly negatively affect me? Or is it not really that big of an overall issue? If I went down to 350, I would have to have another lift and I am not looking forward to that. But if it would overall help my body, I would do it. Thank you!