Needing some input

My nearly 9 lb Yorkie (who is my service dog also) somehow got out of her service dog harness twice now. Though she is very well trained (thankfully) & did not run off, I was still quite frightened about this since I'm in a wheelchair. I ordered a second service dog harness for her since I thought the first was simply faulty, but it happened again. So now, I was thinking perhaps I should attach the harness to a "gentle leader" also?? As a safeguard of course. She's quite well behaved but my fear is a loose, bigger dog being in the vicinity (sadly so many in our community are NOT good dog owners) which would both scare me (since I'm in a wheelchair) & also create a more difficult situation for Sadie to mind me. I'm not all that familiar with the "sizes" of gentle leaders so thought perhaps someone here could give me some input. Sadie is close to 9 lbs, so don't think the petite would fit her. Does anyone here use a gentle leader for your yorkie? Very much appreciate any input dear friends.. xo