I empathize with you.....I was so worried before my first flight with Pico because, even though I had left the (Sherpa) carrier next to his crate for weeks and put treats in it (which he would streeeeetttcch his body in to reach since I put them way in the back), and took him on short trial runs in the car, he never took to the carrier. He never went into it on his own and on the car runs he would scratch at the mesh trying to get out. I was really concerned he was going to make a real fuss on the plane.
But, he didn't. I put him on halter and leash in the waiting area as far away from people as I could and let him wander and sniff to his heart's content. Only at boarding time did I then put him in the carrier and carry him on.
I placed him under the seat in front of me with the open end facing me. If he started to whine I dropped a couple of Cheerios in through the zipper opening. When the engines started, he quieted and slept through the trip. As soon as possible after landing, I pulled the carrier out so he could see around him and he was just fine. Be prepared to get a lot of attention throughout this trip.
TIP: When carrying Pupcake on, raise the carrier high enough for the flight attendants to see Pupcake. If they do not react, boo-hiss, but if they smile and peek in and ooh and aah, there is a good chance they may look the other way if you take him out in flight (after making sure no one in your row objects) and let him nap in your lap.
TIP: When going through Security, dress to pass through without incident by leaving off belts, jewelry, shoes with metal in them, clothing with metal on or in it, etc. I have a "flight wardrobe" just for this that lets me leave my shoes on and walk through easily.
TIP: You will have to take Pupcake (I LOVE that name!) out of his carrier and send the carrier through the scanner. You will carry Pupcake through with you so don't put his collar or halter on him when you leave the house. You can put these in a pocket on the carrier.
TIP: I have a small, thick plastic sleeve with a clip that I place his travel papers in and clip to the carrier handle. This keeps them handy and is time saving because you don't have to fumble for them. Although I have NEVER been asked for these!
Since I fly through DFW, I usually have time to take him out between flights for a quick potty. Then I feel better about the 2-3 hours ahead of him in the carrier during the next leg of my flights.
I believe Pupcake will be just fine. Many on this forum fly with our furbabies without incident.