My first FTP test gave me a 95, so I had the same problem. If your FTP is set correctly you generally want your watts to be on target even if you could do more, especially if you’re doing targeted endurance work like Fletcher. Can you shift to a smaller ring/bigger cog? You’re probably running into a power “floor” with your trainer for the gear you’re in, so it literally can’t go any lower. Are you riding in erg mode (the trainer sets the resistance for you) or resistance mode (you control the resistance with cadence and gearing)?
For the FTP test you’ll probably be fine, because the power will ramp up past the floor pretty quickly. Here’s my first one, when I didn’t even realize my power was off (or that cadence mattered):
I have a wheel-on trainer, and I usually use the small ring and a middle-ish cog. I don’t think there’s a “right” answer for this one (but search around, there’s been a lot of discussion on this forum about it). If the small ring feels good and you can hit your power targets, use the small ring.