Oh my gosh. I didn't know I wasn't supposed to use the invisible thread in the bobbin. I've already made 3 blocks this way and they're intricate and large (16 inches). I guess no one will be the wiser if I do the rest with regular thread in the bobbin but do you think the blocks I have so far will hold up? They look good on the front and on the back but do you think the actual stitching is as strong as it should be?