You really need to discuss with the consultant
A torn meniscus can lead to a buckling feeling, but get the ACL checked by the doctor or your physio
At 18, if you do need surgery for the meniscus, discuss whether it can be stitched or if it would have to be trimmed. If the latter and you can live with it, its best to leave well alone. Menisectomy typically leads to arthritis, you want to avoid if at all poss. Having an ACL reconstruction has already increased that risk, as doe shaving an unstable knee
There's good meniscus info in the information portfolio linked above
Go discuss everything with the specialist, don't rush into anything, lay off the impact sports. Cycling and swimming are knee friendly, running, jumping, football etc. are not if your knee stability is compromised