I've received the equivalent of EE in all the areas of assessment. I'm disappointed with my performance review as I did not get promoted or get a reasonable raise despite my great performance. I (along with many of my peers and my manager) feel that I've already been performing at the next level for the past 6 months. Now it seems that I've to keep performing at the next level for 6 more months before actually getting promoted to the next level - this seems unreasonable to me.
What are my options apart from looking for other opportunities outside my current company?
From the promotion perspective, unfortunately, there's not much you can do. You're at a series C company, so maybe the processes are not as rigid as Big Tech and you could ask for an out-of-cycle promotion. But that is very unlikely.
A more likely outcome (but still unlikely) is to ask for a compensation increase despite not getting a promotion. See this video for more details on that. Your peers and manager think you are performing at the next level -- do you have data to suggest that you're being underpaid? That would help in making an argument.
The best way to gain leverage here is through a competing offer that pays you more. Phrase it like this:
A recruiter reached out to me, I decided to learn more, and I ended up getting an offer. Turns out, this offer is much more than my current compensation. I really like the work I do here, but I also want to ensure I'm fairly compensated. How might we bridge the gap?
If you're well-liked and important, your company may give you a counteroffer. (Note that some companies like Meta also explicitly do not give out counteroffers.)
Amazon actually had a formal term for this called "dive and save". I'd do this only if you are truly ok with leaving your company for another opportunity -- you don't want your bluff to be called and then get stuck.
Resources on negotiation: