The main problem here is that you can't watch two places at the same time, so you have a few options as far as I can see.
My main objective in that scenario would be to delay the terrorists, stay alive and hope to get at least one kill to even things up.
The best use of the smoke would probably be to cover short, as it would have little impact throwing it long where the terrorists can peek around it and use it for their own cover. Throwing it short can delay anyone looking to rush short and give your team time to re-position/rotate. You could even throw a flash through smoke to delay them further.
Once a short smoke has been laid, you have a further choice of where to position yourself. You can either try to hold a position around the A site, where you are covered from one of the entry routes or escape to CT Spawn where you would have additional cover.
Goose would allow you to watch long and not be spotted from short if you're pushed back. You can also, peek back to short if nobody shows at long. If they push through smoke though, you would be exposed as they rush the site.
A Ramp Box: crouching behind the box on ramp, allows you to watch long and again you can check short for terrorists pushing. There's a fair amount of cover in that position, so you would have time between your AWP shots.
Car: as you haven't got intel for long A, it's risky trying to get there as you probably wouldn't have time if it really was an A split. However, in that position, you can hear people at long and peek for a pick and you can also watch short. If you do want to get there, you could use your second flash to flash the corner at long A, and arm yourself with pistol or knife to run faster. On the downside, you have little cover from short.
CT Spawn: I think this would be the safest position to stay alive from if you've smoked and flashed short. Once you've thrown the grenades, you would jump over and down in to CT spawn. The advantages here (other than staying alive and not being rushed are, that you can watch any terrorists that cross near Car and you can hear any terrorists above you and share the intel with your team.
It all depends how confident you are with the AWP and how your team is playing. If you are consistently able to land kills with the AWP, hold a position on site and try to hold them off. If you think you're likely to die quickly as the opponents rush, CT Spawn would be the safest bet.