How to use Match Loudness?

I'm using match loudness after I did all my edits in multitrack. I added effects, manually adjusted volume here and there moving the yellow line on a clip (I don't know what that line is called, it's where you put keyframes) and also added Amplify effect on some tracks. When I run Match Loudness now, the volume is loud to the pioint of being too lound and sounds distorted?  Is it because Match Ludness works on the original recordings and not on the adjusted clips? What am I doing wrong? I'm matching loudness to ITU-R BS.1770-3 Loudness?

Thanks