I qualify this by saying "in my opinion"; if you are four weeks away from hunt time, then don't make any major changes to your bow. Use what you have and continue working on muscle memory, form, etc.
If you feel the pins are just too big and covering most of the pie plate at 45-50 yards, then it'll cover a good portion of an antelope at those distances too. You might want to consider a sight change if this is the case...
I have vision issues and hunt with glasses too. I use a .19 and I'm very satisfied with it; the pins are small and work good in my situation. I've drew my son's bow and the pins on his sight are much larger (I'm assuming .29) and it causes issues for me like you describe. If you're seriously looking for a sight change, then consider a .19 (I use Spott Hogg SDP).
PS - Try using an antelope or cow decoy (made by Montana Decoy) while doing spot and stalk hunts, it might get you closer to that big pronghorn!. I've not used one yet, but will have one in my pack after I draw an antelope tag!