1) You've been stretching for almost two years...not gauging.
2) never stretch with silicone (or put it in a new or freshly stretched piercing. Stainless steel or glass are the way to go.
3) You need to either remove the jewelry or downsize significantly, probably even smaller than 5/8. This will put as little pressure as possible on the fistula and allow it to heal the best it possibly can.
4) I personally would wait 5-6 months before trying to stretch again. Having ripped open your lobe, it's essentially like having a new piercing again and you need to wait until it's completely healed to stretch again, not just until it "feels OK."
5) After awhile you can do massages with jojoba oil/emu oil/etc to soften some of the accumulated scar tissue. This will give you the best chance of being able to stretch up to 3/4 successfully.
6) Lucky for you, BAF sells 11/16 plugs, so when the time comes you can stretch the right way. And there are more than a few threads on here devoted to stretching, I'd check them out.