Hello, are you under the care of an MD Opthalmolgist? I am not a doctor but will just relate my experience. My arc like flash persisted and was stable for 4 months until one day I had the symptoms of a RD (millions of floaters, ink like floaters, intense flashes, beginning of curtain in vision). I had seen my retina opthalmologist several times prior to the symptoms of RD. Dilated exams, schleral depressions. Was diagnosed with PVD, but since I had a detachment in my other eye a year earlier, was told to monitor and get in as soon as I noticed any new developments. So, in the end I ended up with 5 retinal tears in that eye which required a vitrectomy to correct. I would think you have a couple of options.
1). Since you have been seen and assuming by an MD Opthalmolgist just today, watch and wait for anything new and call them immediately as an emergency. They may or may not refer you to a MD that specializes in retina issues.
2). Get a second opinion directly from a Retina Opthalmologist. It would be good to be an established patient with one should you develop retina issues -- also I believe would give you piece of mind. You would then have a relationship with a Retina Dr. that you could call immediately if symptoms change.
I suggest option 2. Anything new I go directly to my retina surgeon although I have some history to warrant this.
With your family history you need to be under the care of Eye MD ophthalmologist. Not non-MD optometrists. You do need to see an Eye MD that specializes in retina diseases. Word on getting into one as quickly as possible. If you see an Eye MD ask him/her to assist with the referral.