Make sure you have normalize off, and are you listening to it on the same speakers after you bounce it or are you taking it to your car or something?
I’ve never noticed or had any of these issues you speak of, it sounds exactly the same from what I hear on the master to after I bounce it down to a stereo track
Don’t export music at 48k, its not worth it. Either stay with 44.1k or double it to 88.2k. I think the 48k is more of a dvd standard with blu-ray at 96k.
A little bit more detail on some of the tips that have already been offered.
I usually keep the volume level so that the meters in Ableton are only 50-60% of the max.
The final output should never clip. Always give yourself extra room to work in. You can make it loud in the mastering stage.
If you’ve done the above you do not need to use normalization on the output.
Output to a 24bit wav for mastering. DO NOT add dithering. Dithering is only necessary for the final mp3 or 16bit wav, and should be the last thing you apply to a fully mastered track. It will change how your song sounds slightly.
Master your track. It’s better to have someone else do it, but you are at a big advantage if you know how to master yourself. You learn a lot that you can use to make your initial mix even better.