Raid is the best source of shards, try to do a normal raid atleast once per week, so far you have only done it twice out of I believe 13 weeks. But there are also other methods of obtaining them: Do daily on Level 28 every day gives you 2 ascendant material (shards or energies). Also I assume your VG faction or other chosen faction should be at the stage where you can buy armor using 65 marks, buy then discard to get shards. You can also get them via public events (common) nightfall (not what you want but common), strikes/crucible (rare), random chests (very rare), Also rank up your other characters to Raid level and you should get three attempts every week instead of only one.