Make sure you're parked in the warm sun so the top is flexible.
Also ensure that you're opening the latches all the way. The farther they open, the farther they reach. If your fingers are behind them, you're likely not opening them far enough. Also use your other hand to pull forward on the header.
Those things along with the sail panels should easily get you half an inch.
This is normal. Your soft top is brand new and should be quite tight. If it was easy, it wouldn't be sealed.