Save your shards for shard "events".  Did you use a new player promo code?  If not you're like me and started in a deep hole.  You're lucky to have two legos.  

What I did and am about to do again is do the quests and missions and challenges almost exclusively.

Yes the ten times per day we are forced into the arena is misery, but if you've gotten a starter promo code and the other one that  just read about, you're probably as well off as you could be.

If you haven't been focused on the quests and challenges and missions that is where you've gone astray.  

Best of luck.  I know it's super frustrating right now.