What type of bow are you planning to make? Is it a pyramid with the 1.75" maintaining a constant taper on your top view down to 3/8" tips. If it is a pyramid, you can have a fairly constant limb thickness because the top view taper is allowing for the reduction in material to allow the limb to bend.
starts at 3/8-1\2-9\16 - 5\8- 3\4-7\8 side view
If these dimensions are referring to your limb thickness, you should be okay to just out of the fades have your thickness at 5/8" and maintain that measuring off the back until you run out of material. The 3/8" thickness is getting close to where your final limb thickness would be. You'll probably need to stay off mid limbs to the tips until you get out of the fades bending more.
do i hang it on a wall with tillering string and pully to exersize it or thin the belly more or the back.
The back needs to be in one grain full length if it isn't already. Don't remove any material off the back at any time after you've got it to one grain. All the removing of material during tillering needs to come from the belly or possibly the sides in some cases. Need to first get the limbs bending some by floor tillering before you put it on a tillering tree. If possible post a side-view picture so we can be sure where the material thicknesses are.