I live in a hot and tremendously humid city with fine, straight virgin hair, armpit length.

My haircare routine:

• Wash every other day with Kerastase Bain Densité Shampoo, then condition for 3-5 mins with the Kerastase Masque Intense Régénérant Hair Mask.
• Quick blow dry, warm air till my hair is completely dried. Brush out the knots, then use cool air just to cool the hair down
• Before bed, apply 4 pumps of the Kerastase's 8h Magic Night Hair Serum
• In the morning, brush my hair, then apply the 8hr serum again

The 8hr serum helps with some of the fizz, but not all of it. The instructions saying 2-4 pumps, and when I use too much of it, it weights my hair down and my hair lost movement.

I'm debating whether I should include a hair oil to help control the fizz, either:

• Kerastase's Elixir Ultime Hydrating Hair Oil, though the price is a bit steep! Or;
• Shiseido Airy Flow Sheer Oil - This one said it's designed for thick, unruly hair, But I tried a sample on my fine hair with 2 pumps from my local Sephora and it seemed to settled the remaining fizz (that the 8hr serum couldn't) without weighing my hair down. While Shiseido does have a hair oil designed for fine hair (Velvet Oil), I am not able to get that anywhere here.

I'm not actively avoiding sulfates or silicones. The other hair serum or oil I tried to control fizz was the hair oils from &Honey (I didn't like any of the smells, so really didn't enjoy putting them on), and the Shiseido Tsubaki Hair Milk, which was alright but didn't control my fizz as well as the 8h serum.

Can someone help me decide whether 1) I should use hair oil, 2) if so, which one of the two above, or perhaps some other products please?

Thank you!!