Why do I always get -1 Level?

Your giveaways get retroactively bundled probably.

What TheLuckyShamrock said.

Game(s) that have given you full CV can be bundled and bundled games give you only 15% CV instead of full CV.

The other option is the games you have given away may have been reduced in price on Steam. Your SG level is based purely on current prices for the games you have given away.

Goblins are stealing your exp.

Third option:
You get hit with Steam store price glitches. Because as kelnage said: "Your SG level is based purely on current prices" if the store price changes or the Steam API goofs up and returns the wrong price for no good reason, that will also drop/raise your CV until the glitch gets fixed.

Thanks for replies, maybe on the next giveaway everything will change.

Beep and Defy Gravity Extended are regularly going into some Steam-bundle, boosting their base-CV from 2 to 15. During the time of this bundle you will have Level 2.

Out of curiosity... any easy way to know which of your GA's had the CV drop (aside from just being familiar with the numbers / manually tracking each)?

Good part about being lvl 0 - you cant get -1 lvl

I recommend this tool to help you understand your level. OSS (Ouinx2's SpreadSheet) - Tool to plan giveaways on Steamgifts