Bonjour from Montreal!

[Owlie]

Thirding the call to run a lower tire pressure. I have an aluminum frame (road bike) and I run around 100PSI in both tires on smooth pavement. (Yes, I can get away with less, but it's easier to just to top up both to the same amount.) I had a tire on the rear that said minimum PSI was 110. I still ran it at 100 and had no problems. (I'm around 135-140lbs)
And you can totally put 25mm tires on a road bike. That's probably about as wide as you can go, but 25s shouldn't be a problem. I can't imagine why the LBS would tell you that you can't.

Other big thing: Relax. My first couple rides on the road bike were terrifying, and mine is a "relaxed" geometry bike. Yours is pretty aggressive. It's engineered to be light and responsive, so if you're tense, that means that every little twitch gets transferred to the bike. On a road bike, you steer more with your core and body positioning than with the handlebars. Those come into play for low-speed turns. If it feels really twitchy and difficult to hold your line even after you get used to the bike, it may be because of a very short stem. (It's become a thing, these days, to put a very short stem on women's and small unisex road bikes to make the reach look shorter.) If the reach is an issue, I'm not sure how much you can do about that other than adapt. (I have a slightly-too-short stem on my road bike. It's a little wigglier than I like, but my shoulders don't ache anymore!) It took me a long time to get comfortable with my bike. I think it was around 1000 miles that I felt really comfortable. For you, it may be sooner, it may be later.

And no one is going to post on the internet about how their carbon bike didn't fail. Yes, failures happen (and sometimes they're rather catastrophic), but it's relatively rare, and NYbiker has pretty good advice.