Nephew Reunion Wanted

Hi, I would like to reconnect with my nearly 18yr old nephew, but don't know how to reintroduce myself... The last time I saw him he was 5yrs old. Until then, my family provided childcare when parents worked/ went to school (he knew and loved us). My brother(biological father) was a loving father and they shared a strong bond. However, the relationship between my brother and my nephew's mother was very tremulterous. My brother lost a custody battle and parental rights (while in jail(unrelated charges)). Soon after, my nephew was adopted by his stepdad. I don't want to cause any issues or intrude. I understand his mother's concerns and actions, back then. And, I am thankful for his stepdad providing a seemingly good life and upbringing for him. Most importantly, I don't want to cause trauma or psychological distress to my nephew. I still love and miss him very much. My husband had an upbringing nearly identical and encourages me to reconnect. My husband also has many connections in the sport my nephew competes in and we have learned that some of our friends children are actually friends or acquaintances of my nephew! Through word of mouth, I've discovered we live very close to him. I could really use some advice on what to do with reuniting. I am worried about feelings his mom and stepdad may have or try to restrict our family.Our family is very small. My nephew has an older sister (he knew), a grandma (my mom), and me. My brother isn't living in state. At this time, I'm not attempting to reunite everyone. I prefer to let my nephew decide when or if he'd wish to do so. I wonder if he'd remember us or thinks of us. I have a son I'd love him to meet. I am so nervous and on the fence on when, how, and/or do I even move forward with trying to reconnect. I could really use some advise good or bad. I appreciate it :)