Welcome to YT and congratulations!! Addison is
gorgeous ... and
all Yorkie, IMO! Sounds like he has settled right in and that's wonderful. Sometimes it takes them a long time to learn to "trust" and understand that there are loving people who are honored to have them share their lives. Most rescue's have a certain look in their little eyes and there's no greater reward than the day that look is replaced by one of trust and love!
God bless you and your husband for loving a rescue!!