You tested the Lotus and loved it. It's $100 cheaper than the TRS. I don't see what the problem is.
At 105 pounds, you are already pushing the limits of what a board can do for you in terms of stability. Any longer/stiffer and the board will really start to work against you. Why add a men's flex to the equation?
Have you taken a lesson or lessons from a certified instructor? I don't mean to be rude, but the notion of a 105 pound female riding intermediate terrain on a 155 cm board is just ridiculous. 155cm for a 105 pound female is big mountain, advanced riding. Shayboarder, a bad ass, excellent female rider who keeps a very respectable blog about snowboarding, rides a 157 Lotus. She totally rips on it, but she also weighs close to 200 pounds. Sooo.....I guess what I'm saying is take a look at your technique and make sure your board isn't riding YOU or that you aren't swiveling that tail around to make it work. At some point, the negatives of a long board outweigh the positives. In order to be stable, you need to do as much or more work as the board you're riding.