Breastfeeding also suppresses ovulation for months following birth; this means that the amount of oestrogen circulating in the body is below normal levels, which causes vaginal dryness and a general dampening of libido. Perhaps ask your doctor about post-partum depression, since symptoms in mild cases include a lack of focus and loss of sex drive.
To help perk up the sex drive, let your mind wander to a wonderful fantasy that turns you on. Then give little delicious details about it to your partner. You may find you can relax by discussing a highly erotic fantasy storyline and fall into the moment.
Ask someone you trust to babysit, to simply give the two of you some quality time, a date night if you like. Don't discuss the baby, this is your time. Instead talk about the things you enjoy together. This time doesn't have to be for having sex. Go for a walk or watch a romantic movie together. Let your partner know how much you love him; that you are a little mentally or emotionally overwhelmed by all the changes a baby brings.