I thought boy right away!! After seeing between our little girls legs there was definitely 3 lines, with yours there is no 3 lines and what seems like an obvious external extra bit!!!
If you are worried can you get another normal scan?
We got a 3D one as well at 28 weeks and so worth the $200 to us!! It was awesome to see her face and her little lips and hands and feet!! I loved it! We drove from Toowoomba to brissy to get ours done too so understand the traveling bit!

Good luck and let us know what happens but I'd personally say you're having a boy!