My wife is 13 weeks pregnant and the feeling of being a father has still not sunk in. How can I help her in this period and how can I make her feel more comfortable

At this delicate and happy stage, your wife needs you the most, both physically and emotionally. A wife becomes a mother since the day she conceives but for fathers it takes some time for the feeling to sink in. Its good that you realize that you need to make your wife feel special. Go for all the doctor checkups with her, take her out for outings, cuddle with her and talk to her about the baby and her feelings, share yours. Cook something special for her. Read books about parenting and babies together.