Questions about my martial arts experience and training...?

som im a 20 yr old male. i formally practiced tae kwon do for about a year and a half when i was around 13-14 yrs old. i had stop stop after i entered high school as i no loner had as much free time. i was really good at it (maybe op 5 in my class) and often won competitions and such. If im not mistaken, i was 2 belts away from black. Its been at least 6 years since then, but i was thinking about it the other day, and i would really like to start training again. (not formally though, just on my own). i sparred by myself a bit in my basement and i surprisingly still remember a lot. obviously i was very rusty (especially in proper form and flexibility) but i still think i can start again and pick up fairly fast. What do you guys think?? i this possible or will i have to start over again with classes and formal training??