First, congratulations on your approaching graduation with the Bachelor of Architecture.
Also, I applaud your career goal of becoming an architect and passion for urban design and planning. As you begin to research firms, you will find that many firms provide both building design and urban design services. One such firm is Ayers Saing Gross -- http://www.asg-architects.com/ -- However, please be aware that there is a difference between urban planning and urban design.
While the two fields are closely related, 'urban design' differs from 'urban planning' in its focus on physical improvement of the public environment, whereas the latter tends, in practice, to focus on the management of private development through planning schemes and other statutory development controls.
Which is your passion?
As you are obtaining the professional degree, I would suggest you find employment for a few years before returning to school for a post-professional degree (M.S. in Architecture). If you search ARCHSchools.org, you will find more than 75 programs that have a speciality on urban design but a few programs that immediately come to mind are Notre Dame, University of Miami, and University of Maryland.
Keep talking with your mentors, professors and others to continue to refine your career goals and implementing them.
Lastly, if you are interested in urban planning, but in touch with the American Planning Assn.