Urgent WordPress Speed Boost

I need an experienced developer to fully optimize my high-traffic WordPress website.

Cache Hit Ratio only ~53%
Sudden spikes in requests (bot/DDOS traffic)
Using Nginx + PHP-FPM + MySQL + Cloudflare (Free Plan)
WordPress with MyCred (PayPal IPN integration)

Problems:
Site is slow and sometimes goes down under high load.
Cloudflare cache ratio is low – server receives too many requests.
PayPal IPN breaks when Cloudflare "Under Attack Mode" is enabled.
Bots generating huge request spikes (6M/day → 98M/day).
Need to optimize database, server, and caching rules.

What I need:
Full server-side optimization (Nginx, PHP-FPM, MySQL tuning).
Cloudflare configuration (Page Rules, Firewall, Bypass rules for login/IPN).
WordPress optimization (caching plugin setup, image optimization).
Bot protection (Firewall Rules for XMLRPC, wp-login, API abuse).
Increase Cache Hit Ratio from 53% → 80–90%.
Ensure PayPal IPN works reliably with Cloudflare security enabled.
Reduce bandwidth usage without breaking functionality.

Requirements:
Proven experience with WordPress performance optimization at scale.
Strong knowledge of Cloudflare (Free/Pro) + Nginx + MySQL.
Ability to secure site against bots and reduce unnecessary requests.
Must provide clear documentation of changes.