The meter neither knows of nor cares about whatever processing precedes it. It's merely reporting a measurement of the audio at that point.
Do not be concerned that the peaks on your master bus are "low". This is irrelevant in the ranges you're describing. Instead, be concerned about the peak-to-RMS
ratio, which is an indication of the perception of transients (e.g. drum hits) against the backdrop of average loudness. You of course want that ratio to be high enough that transients are clearly audible over the rest of the mix ("punchiness"), but it is in fact possible (and common) to start with an
excessive crest factor (ratio) that requires
reduction. Lowering that ratio is the compressor's main job.
The mastering phase is where you bring everything up in volume. This is normally accomplished by sacrificing peak amplitude in order to raise the average volume, and is accomplished through compressors and their more-aggressive siblings, limiters. But that's a separate step that occurs after the mix is done. During the mixing phase, just get a sound you like and don't sweat the numbers unless it's clipping. In fact, it's
good to leave some significant headroom while mixing; -8dB is actually a reasonable target for an unmastered mix.
If you find that applying compression sucks life out of your mix, then dial it back by increasing attack times and lowering compression ratios. Or take the compressor out altogether. There is no rule that says you need compression at all. No record ever lost a Best-engineered Grammy nomination because it was under-compressed.