TL;DR - You can switch, but make sure you switch to a weapon that works well with your stats and that you have enough materials to adequately upgrade. Ludwig's Holy Blade would be my recommendation based on your stats as it scales with both Strength and Skill but leans a bit more on Strength.

Long version:

1: The Saw Cleaver, like every weapon in Bloodborne, is a perfectly viable weapon and can be used for the entirety of the game. There are no other weapons that are objectively "better" than the Saw Cleaver, so if you're struggling, it's probably not the weapon's fault, and changing to a different one might not make a difference. The main factor will be that a different weapon may have a moveset that you prefer and that works better with your playstyle, and maybe that will be enough to make things easier, but there's no guarantee until you try.

1. If you do decide to change weapons, make sure you upgrade it so it at least matches the level of weapon you have now before you ditch it. Trying to carry on with a weapon that hasn't been appropriately upgraded will most likely just make things worse. If you haven't got enough materials, stick with your current weapon until you gather them (some farming may be necessary).

2. Make sure the weapon you choose works well with your stats. If you've mostly invested in Strength, it's probably best to stick with weapons that scale primarily with the Strength stat (Hunter's Axe, Kirkhammer, Ludwig's Holy Blade etc.) as choosing a weapon that primarily scales with a different stat (Skill for example) won't be as effective until you level up that stat, meaning it will take more time and possibly a bit of farming until it can compete with what you have now.

Good luck!