Should I go 45mm instead?

I also have 7.5 inch wrists band can not pull off a 45mm watch but it depends on the shape of your wrists, and you seem to be able to pull it off. I would go for it.

Wrist circumference is a somewhat misleading--or, at any rate, incomplete--measure here. The shape and proportions of the wrist would be crucial in determining how watches of different sizes look on it. In particular, it is the width of the 'flat' surface on top of the wrist, on which the watch sits, which determines how it looks. It can be wider on a 7 inch wrist than on a (differently proportioned, rounder all around) 7.5 wrist.

That part of the wrist indeed appears to be particularly wide in your case, making the 42mm watch look tiny--more like a 38. A 45mm watch would not look remotely too big on you, IMO. Which look you prefer, however, remains a personal choice.

If I could pull it off, I would go for the ploprof. If you are more into sports watches, they are a beauty and very different.

NO! That watch looks perfect on you. Any thing bigger and it will make your wrist look spindly.

Beauty is in the eye the beholder, but I can't believe people are telling you to go 45.5. What you have on your wrist looks excellent. 42mm is a big watch. It is not small. On you it looks ideal.