Sertraline - Why would my doctor up my dosage?

Hi! I am on 25mg. And 2 days in. Not sure if its working yet. But last night was tough. Insomnia.

25mg/day is the low initial dose for panic disorder; 50mg/day is the usual for depression and anxiety disorders. Since the maintenance dose is 50 ~ 200mg/day you may require an increase at your doctor's discretion... 25mg may or may not be therapeutic for you as every person responds differently to the medication and there's no set dose for everybody.
Insomnia is very common when first starting treatment and affects about 20% of all users. The good news is that side effects generally resolve within just days to a week or so and tend to lessen day by day. If it persists longer than that let your doctor know.
It's very important that you stay in contact with your doctor during this initial phase as your metabolism adjusts to the drug. You should report any side effects and the progress you're making.
Most people will begin seeing the positive effects within the first two weeks but it may take 4 ~ 8 weeks to feel the full benefit of the drug.

Thank you so very much. I will make sure my doctor is aware of all. I am hoping I can live with just taking 25mg as I have never taken any antidepressants. I just had my 3rd dose and feeling a bit shakey, hungry and sleepy. But I am wondering if that's because I am having trouble eating. My mood is a bit better but I still have that cold nervous gut feeling of anxiety. I am just so desperate to feel better and I cant speak to my doctor when ever I want I have to make appointments which could take days. I greatly appreciate all the advice and encouragement I receive from this site. And Thank you for your prompt responses.

You're quite welcome! We try to be of help so if you have questions or concerns along the way please feel free to post again.
It might be good for you to know that sertraline is one of a very few antidepressants that are FDA approved for both depression and anxiety disorders. It's a good choice.