A psychiatrist is much more knowledgeable than a GP when it comes to these types of medications, chances are if it worked before it will again. You should feel a differenece in 4 to 6 weeks, if not, start the 20 mg.
Take care..
YOU are the only one who will know if the 10mg works or not. I would definitly give it a try. You have nothing to lose. If it doesn't work, you can up the dose and if that makes you feel "not like yourself," you can try something else.
Best of luck
Peace
Greenlydia