It is different for everyone. You have the right attitude. Go up to the 20 mg and use the Xanax when you need to. That is all we can do until the medication starts to really work and as you have read on here it takes 4 to 6 weeks. When you have the "heart attack" feelings, are you practicing your breathing technique? It should really help bring your heart rate back down.
My GP and my therapist said that 15mg isn't even a therapeutic dose and I'm just prolonging the side effects by waiting to go to 20mg, and since I've been on the 15 for 5 days, tonight I'm just going to start the 20mg. I was up at 6am thinking I was having a heart attack from the anxiety. Nobody thinks it's from the Citalprolam so, I guess I will just try and see. And I'll just keep on with the xanax if needed.
Yes, unfortunately a lot of these medications have anxiety as a side effect. You are almost two weeks in. Even if this is not your target dosage, I think that you would start to see some of the side effects decreasing over the next two weeks or so. Many of us have had to supplement with xanax or klonopin in the beginning due to the anxiety side effects so know that you are not alone. If you think you can get away without the benzo, try not to take it so that you can really see if progress is being made with the citalopram.