The feeling of lethargy (and foggy-brain) stayed, significantly, with me until about six months at which time both began to gradually lift. Lethargy and foggy-brain are not uncommon in early sobriety. Have faith, it will pass but 'in time' - how much time seems to vary from person to person.
I experienced quite a bit of 'drinking thinking' early on, also, that focused on sober-time, exposure to alcohol, etc. Once you grow your sober-skin, these thoughts will dramatically reduce in frequency and intensity.