Before going public on Facebook I had the same thing. What I think caused it for me was signing into the Facebook app on my phone, which then looked at all of my phone contacts and made suggestions from there: People I haven't spoken to from previous jobs in a very long time, service reps I had worked with one time literally ten years prior but their info was still lurking in my phone contact list........... along with several people I had met at support groups/girls night out events/texting friends I had met online/etc......
I was like you, freaking out about the suggestions and didn't want them outing me before I was ready. In the end as far as I know they were only visible to me and I never acted on them so they never became an issue.
One thing that had occurred to me when this happened: How many of these suggestions that I am seeing are people that I have met at a support group or whatever but I'm now being shown their "male" persona on Facebook? (There were quite a few suggestions I got of people I couldn't recognize and to protect anyone else's privacy I never tried either out of respect) And even more troubling: How many of these people are seeing *my* male persona as a suggestion because they have my phone number too?!?!
No one ever contacted me so I guess I'll never know but I always wondered.
Now that I'm fully out, living as me, and my Facebook account has transitioned with me I'm not concerned at all anymore, I have no secrets left. Which has been a wonderfully liberating experience. To sound cliche: I hadn't realized how great that weight was to carry until it was gone.
Short of doing what you did and deleting/suspending all Facebook accounts the best that can be done is to lock down the privacy settings as far as you can and hope for the best.
