96 corolla rear wheel bearing leaks?

Greetings friends.
OK, I was getting some whirring noises for some time from my rear wheels and then thin thread-like grease splatters appeared on both my rear wheels last month and a friend told me my bearings are leaking. So, since I had over 200,000 miles on these bearings, I decided to replace the bearing assembly on both wheels myself taking only 2 hours. The Haynes manual mentions an O-ring but doesn't say how to install it or is it inside the assembly already?? I torqued all four bearing bolts and oiled and torqued the wheel lugs. After fifty miles the whirring noise I use to hear is gone but the grease splatters are still appearing.

Please, what do I do now? thanks