La Sportiva FInale sizing

A few months ago I bought a pair of Finale's while out of town. The sales guy sized me, and ended up convincing me to settle with a pair of 42.5's. They've never been comfortable - my toes go numb after about 10 minutes, but I've only used them about a half dozen times. I wear a US size 11-11.5, and the conversion chart I just found online compares 42.5 with US 9.5. That seems like a pretty dramatic difference. Did I go with a far too small pair of shoes, or do I just need to power through the break-in period.

This is my first pair of climbing shoes, by the way.

Thank you, folks.

Edit: I'm using these bouldering outdoors.

I have some. 1 size down worked for me.

I wear a size 9 street shoe and my first pair of climbing shoes were a 42. i gradually sized down as my feet got used to a smaller sized shoe. You might have gone to small for the first pair. If you can take them on and off between climbs they should stretch over time to a full size bigger than what you originally had because of full leather construction. 

i wear a 11-11.5 street...and my Finales are 44.5-45.  

i mean, i see how you COULD size down to a 42.5 maybe, but it seems a ridiculous amount of aggressive downsizing for such a comfy flat shoe.... especially since it's your first.

they are full leather and they do stretch a fair bit... but I think the salesman undersized you there.