To make things short

 

Although it may sound like its holding up fine, it'll eventually blow due to the bass notes. The OEM speakers are rated at 15 watts, just replace them when they go out...

 

my bass is at 0...

 

IMO adding a small amp would benefit the longevity of your OEM speakers although this would be overkill to spend money and keeping the original speakers.
You could add an amp now and probably realize some improvement and some protection but your next upgrade would definatly have to be better spreakers.

 

if you don't hear audible distortion, you're not damaging your speakers.
even if you do damage your speakers, you're covered for 3 years/36k miles.
And if you can bear to listen to the stock stereo for 3 years or 36k miles, you're
a stronger man than I...