If you're in Northampton you're kind of on the border of 5C & 3D and not far from opportunities in 4C.
For 5C, hop across the Lehigh River and start exploring SGL#205. Further west towards Reading is Blue Marsh, it's huge. Ontelaunee Lake and Leaser Lake offer public hunting grounds. Jacobsburg State Park near Nazareth offers hunting but anymore it's like a glorified city park or dog walking park. I stopped hunting it several years ago because of this.
In nearby 3D, you have Beltzville State Park and Wildlife Management Area. Lots of room to explore and hunt. That should get you started.