I was going to submit KeelieThompson1's Faithful Compass series (it's one of the best johnlock five imo) but I think it might have been deleted. Do you guys or anyone else know if it's still around?
You need an AO3 account to view it. That may be why you couldn’t see it. Otherwise, google is your friend.
The Faithful Compass (Series - 300 444, total)
John is five/six years younger than Sherlock and is studying at university when he meets a bored, addicted Sherlock. But Sherlock still needs to become sober, learn his skills and become the consulting detective while John needs to train, find his place in the world, and in the army, to become the man that can match Sherlock. The problem is they may not be able to become these people while in a relationship with each other.