IHF thank you for posting those links – they were really helpful, I printed them up to keep in my sketchbook 🙂
OP, I’m only an amateur but a couple of things about your portfolio that stood out to me are:
Some of the faces seem a bit over exposed. I think you cross the line between going for bright and punchy into being somewhat washed out and detail and definition begin to get lost.
The black and white images all seem rather flat, imo. Different lighting is required to make a black and white work, light which provides more contrast and/or a wider tonal range. I think it would help you to study photographers who excelled at b+w portraiture for inspiration and to understand what makes a strong b+w, Yousef Karsh did amazing b+w portraits.