Lymphodema Professionals

If you're noticing any enlargement in the arm, it would be best to get it checked out as soon as you can.  As @afraser says, you would normally have had some sort of measurement done.  Even if that hasn't been done, you can have the fluid in each arm compared.  I haven't gotten one yet, but apparently (according to the lymphoedema specialist who spoke at the Adelaide conference) you can get a round knit sleeve from a chemist to wear until you get checked out.  You have to get the right size.  This is not one of the fitted compression sleeves but should help until you are able to get in to see someone.  I can recommend a couple of places in Adelaide for specialists but don't know for other places.

You would usually have an initial test for fluid and measurement to ensure that any changes can be monitored and assessed. Exercises can certainly help.

I would seek out a Physio who specialises in lymphodema. They can give you exercises specific for you and also tell whether you are heading for lymphodema or not.