I was like you with the nervous shopping and getting out as soon as possible with my reward in hand for being so bold for many years.
When I came out to the wife after the usual discussions and answers, she began going shopping with me and it was fantastic to have a females opinion. She helped me for about two years then one day said it was just my thing and I would have to shop alone. Now I still go in stores less nervous than before but shop online if I know the size will fit.
Hope your wife continues to go with you.