I currently have a B1/B2 visa valid till 2020. My Husband is in the US currently working under his OPT. I would like to visit him on a tourist visa. Can I travel on my B1/B2 visa? Am I allowed to stay for 6 months or 1 year? Can I by any chance extend it from the US itself? Also do I need an invite letter/ sponsorship from my husband for me to travel on B1/B2 visa?