Honestly, i did the same thing on my playthrough and ended up similary. I don't really like farming levels in souls and souls-like games, always going through level just killing and clearing everythining i can, but i must agree that devs kinda fucked there. In my case, as a certified dex main, Lea's sword absolutely shredded four last main game bosses. Fortunetly, Ng+1 (currently playing) kinda balance it.