play in front forks..

If everything's tightened as much as you can, it could be you've lost either a spacer or part of the headset - bearing covers maybe? It's certainly not a new fork needed though. If you're as ham-fisted as you've made yourself sound, get it checked out by the LBS.

Back the screws on the steerer off a bit, tighten the crown screw with a 5 Nm torque key. Tighten the steerer screws back up, jobs a good'un I reckon.

This is basic stuff, anybody can do it.

The Allen head on top of the steerer adjusts preloaded only. The Allen heads which are horizontal hold the stem and handlebar.

Step one -slacken off the horizontal Allen heads (not so much that they become slack)

Step two- adjust the preload (free play of forks), gentle turn clockwise top Allen head. I apply front brake and rock the handlebars so I can see if there is any play. once adjusted check for free movement in turning front wheel. If it's notchy slightly loosen off top Allen head. Repeat these steps until satisfied.

Step three - tighten up the horizontal Allen heads which hold stem whilst check they are in line with front wheel

Job done there will plenty if youtube tutorials re any aspect of bicycle maintenance.

Loosen everything off then tighten the top cap first until there is no fork play, but not over tight. Then tighten stem bolts.

However you need to use the correct torque setting, especially if you are working with carbon parts.

You probably tightened the stem bolts before setting the headset preload. But as you're not sure if there's a piece missing you're probably better off taking it to the LBS.

Take it to your LBS now. Don't ride it.

How much play are we talking about?

Probably just not tightened it all up properly?

This might help:

https://www.youtube.com/watch?v=1P4dYsxazTU