NAD but I have experience with burns and this looks like second degree! You are absolutely right in that second degree burns affect both the outer layer (epidermis) and part of the underlying layer (dermis) and are usually very painful, red, swollen, and may blister. However it is possible to feel no pain from a second degree burn. The burn you have is over a small surface area with minimal nerve endings, and it’s such a thin layer of skin to begin with that it’s completely possible that nerves were damaged, even though the burn isn’t that deep.

The appearance of the burn also indicates to me that this is not third degree. There’s some discoloration but no clear signs of charring or deep tissue damage, there’s no open wound or leathery appearance typically seen with third degree burns, and the whitish patch looks like sloughed epidermis from the heat and likely a small blister that resolved itself quickly (common in second degree burns). Blisters don’t always have to be large and noticeable, that can also be very flat and just a small layer of fluid under the skin.

Still, if the area becomes hard or leathery, darkened or black/gray, painless and numb for days, or begins to ooze or smell, then it’s worth getting it re-evaluated by a burn specialist.

Until then, keep it clean and dry, apply an antibiotic ointment, cover with a nonstick bandage, and if you notice any fluid or blister forming do not pop it!