Welcome to the QB from SE Michigan! If following a standard quilt block pattern for a finished 6" block you should have the 1/4" seam allowance all the way around making your block 6 1/2". The reason that a block usually comes out at 6: is the seams are more than 1/4" when sewn together. It is not uncommon for this to happen even for an experienced quilter. Don't panic. If all of your blocks are 6" then make your quilt and the finished quilt will have 5/ 1/2" square. No pain no gain. I can guarantee that all of us have been there. Next time around adjust your seam allowances to just a bit smaller you will get that nice 6 /12" block. I am glad to see you have jumped right in. Looking forward to seeing a lot of you on the QB!