Sorry about your predicament. Your law school credentials are excellent, as you have explained nicely. I think your last good shot is to make sure you land a solid clerkship. Usually, clerking is not the way to go to land biglaw if you're not able to through OCI, but that is usually because people who resort to that don't have the numbers in the first place for biglaw, but you do. So it seems like post-clerkship would be a somewhat viable option for you. I mean, what else have you got, besides that and networking?
In the meantime, something has gone seriously wrong, and you need some realistic introspection. I mean something concrete went wrong, and it's not just bad luck. So you must figure that out. Common culprits might be way below average interviewing skills, really poor bidding, giving off a vibe of entitlement, really poor application docs, or really late timing. I can't possibly think what else it could be, because everything else seems solid.
Are you in a hyper-competitive market?
If I were you, I'd talk to like 5 different people you respect and get their honest feedback so that you can fix whatever went wrong. You seem too smart, hard-working, and gunnery (in a good way) for this to just be bad luck.
Hope it works out!