Lost item with new game ?

Hello everyone, First post for me on Reddit ;)

I recently bought Diablo 1 on GoG, to go back in time and finally finish the game that I could not finish in my youth (was 10 at the time).

I made a warrior and am currently lvl 19 and I just cleared map 12.

I have a lot of difficulty on map 13, and was thinking about starting a new game to get better gear.

My pb is that when I start a new game, all my gears and inventory are still here, EXCEPT for my armor.... So I have my helm, amulet, sword, shield & rings but my armor is replaced by a mana potion.... Even if I put my armor in my bag instead of equiping it, it disapears...

Do you guys have any idea???

Thanks a lot!