Double Expertise

Hi, i have a simil issue: i've build a scout rough, with a ranger biclass. I have (with scout) proficiency in survivor (+3), and that give me a x2 of proficiency bonus, that's means is a +6, but, because i have a ranger (before beeing a rough) i already have a survivor proficiency. With the first level of ranger, i use the optional feature of tasha to use (expert explorer) that give me a x2 in one of my proficiency that i choose, and i chose survivor, so i have a x4, thats a +12. When i chose rough, i have to choose a proficiency that i want to give a x2 at proficiency when i roll (maestry), but, if i chose nature, that's give me a +24!!! if my basic stats in Winsdom is +4, i have a +28. Sorry for my english, but can someone say to me if i'm wrong