Seems like these results are consistent with each other, 3.66s and 3.52s are very close, if you repeat the test few time and all results are around those times you should consider around 3.5s as the realistic loading time for your users.
Have you checked your analytics account for the site speed section?
My favourite tool (developed and supported by Google) is webpagetest.
If you check your website with it you will notice few area of improvement, in particular the TTFB (Time To First Byte).
The two metric you should care about are TTFB and the total page loading time.
- TTFB is a factor in google algo ranking of your pages.
- The total loading time is affecting your UX, and potentially damaging your bounce rate.
In the webpagetest your site is getting an F for TTFB, which seems to be between 3 and 7 seconds. Which is really bad and potentially hurting your SERP ranking.