Am I a "Wicked" Stepmother?

I have two stepsons ages 10 & 7. I have been married to their father for two years and we share custody with their mother 50% of the time. The boys are very bonded to their mother and I am very happy about that. I want them to enjoy a strong relationship with both parents.

Due to the nature of my husband’s job, I am usually the boys’ primary caregiver. I find my role as a “stepmom” to be a very difficult one however. I care for the boys, and I am very attentive to their needs, but I don’t really feel all that bonded to them nor do I feel that I “love” them like I do my own children (they are already 17 & 19). Is this normal? Am I a “wicked” stepmother? What are some ways that I can overcome these feelings or do I even need to?