Have you tried a gelatin PT on your hair? You can add gelatin (pure protein) to FSG. I haven't tried it in FSG yet, but I love IAgirl's gelatin PT so I think I'm going to go for it in my next batch. Searching for "gelatin FSG" came up with a lot of results. Here's one: Experiment - new FSG, great results so far!

I made two batches of FSG so far, so I'm no expert either. But I love how my second batch came out. This will sound really gross, but it's kind of the consistency of mucus... it looks liquidy at first, but it's deceptive. If I put a quarter sized amount onto my hand and pinch it with my fingers, I can pick the whole thing up in a booger-like glob... but it's magical in my hair! I keep it in a clear plastic condiment squeeze bottle (like Amazon.com: 12-oz. Squeeze Bottles 3 pk. - Clear: Home & Kitchen, but I bought one at a local kitchen store for cheaper) and it is really easy to use from there.

I wouldn't describe the consistency as a serum. Maybe it's between your two batches consistency-wise?
2b/c, high density
fine, medium porosity, normal elasticity
loves protein, hates polyquats
still searching for HGs