Esteban 0-2 years

A. Esteban is overall a happy and healthy baby boy. He is quite active and not really into sleeping a lot. He eats well and is securely attached to me. I sing to him, rock him, cuddle him, soothe him and tend to his every need. He is not as securely attached to my partner. He works a lot and is supporting us while I am on maternity leave.
At 3 months, it is time for me to go back to work. This seems to have created a little stress both for me and Esteban. Esteban does not take easily to other adults. My niece has moved in with us while she works to save money for college. This helps me and my husband out and is much less stressful for Esteban. This lines up very well with Bowlby's attachment theory. Esteban often cries when I leave and turns to me for comfort. Esteban quickly forms a bond with my niece and his world seems to be good again.
At 8 months, Esteban becomes fussier, which stresses me out more. I have been under a lot of pressure at work lately. I continued to look for ways to soothe him.
B. Esteban is very physically active and is highly interested in his surroundings. He is pretty even keel when it comes to his emotions. He only really cries when he's hungry, tired or when he needs to be changed, which is pretty normal. He continues to shy away from new adults when he first meets them, but eventually he comes around. Esteban like to socialize with other kids and plays and "talks" with them. He has been socializing with the little boy who lives across the hall from us on a regular basis and has met new friends at the park. Esteban is generally very cooperative. He plays well with other children and only throws a temper tantrum on occasion. Esteban is generally able to pull himself out of his moods on his own. It is rare that he is put in time-out for any reason. Over the last 18 months, his temperament has been pretty stable. He does need to work on building things with blocks etc...
I have the tendency to change according to Esteban's moods (goodness of fit). This is something that I need to work on. Instead of me changing for him, I need to help him adapt to his environment.