Hi. Some of the items I ship are in 8x6 envelopes (the largest size allowed by USPS to still qualify for envelope rates) and weigh 2 oz. These cost 85 cents to ship with a stamp. If I make a sale through Etsy, I get a small shipping discount of about 10 cents, and gives me a tracking nmber. However, when I put these dimensions into Shopify to create a label, it comes up as needing $1.20 in postage (almost 50% higher than necessary) and no tracking number, which I also automatically get when purchasing shipping through Amazon or Ebay. Any ideas why this is happening and how to fix it? I can just use stamps, but I really would like the tracking info as well, plus I don't want the hassle of constantly having to replenish stamps.