How many fixtures on a wet vent?

is there any thing else draining into the 3 inch pipe thru out the whole house

put a 3 inch wye on its side turn a 3 inch 90 up into wall cavity under floor reduce to a 2 inch then run up through floor into wall cavity then plumb it in as picture and the off top of t where wash machine trap is reduce to 1 1/2 vent run up above height of the sink a foot or more then run over to sink vent and ty into it with a sani t. now if i remember correctly the vent size should be 2 inch or larger the rest off the up off the t where sink vent and wash machine vent ty in together, but a 1 1/2 will work
http://newhome.michaelwardonline.com/wp-content/uploads/2009/08/New-House-117.JPG

and get ready to hear how this is not code but it will work