That's not quite right.
The straight after the right turn after the Casino is much shorter and straighter.
I think you turned north too soon. I think you can see the Casino on the image, further east. The left at the top of the hill is immediately in front of the Casino.
Then you had to go too far to find a straight, and I'm pretty sure the hairpin your created is not at the Grand Hotel, and you return way too far east.
There's a well-known traffic-circle-type-thing in the inside of the right-hander after the left-hander at the top of the hill. (Actually, perhaps
that's Casino Square?).
Is there another Monaco map thread somewhere here?
Compare with...
http://www3.monaco.mc/monaco/gprix/circuit.html