Only Have One Central Incisor... What to Do? (photo)

It appears you still have crowding issues as well as a posterior crossbite on the left side. Depending on your age palatal expansion will open up space to bring the central tooth into the arch. Then cosmetic dentistry can reshape both centrals as needed. There are "quick fix" options available like 'snap on smile' for short term results as well.

I highly recommend you get braces and do exactly what they told you at the orthodontist.  BUT  you can do something temporarily with some cosmetic tricks( for the time being). You could have a dentist who is very cosmetic oriented, reshape 9 a bit -bulid out your lateral 7 to match 9 as much as possible to look like the missing front tooth and get a little more balance until you can wear braces!  Have a cosmetic dentist do a wax up appointment to try it-Good luck-