Even if you love your current phone, I suggest to upgrade to a more modern phone. Even if you can move your apps to SD Card, not all apps will allow you to do this. When I had my first android phone, Motorola Backflip, it only had 256MB of internal memory. I used a 16 GB SD card and after a year, I had to delete apps because of running out of apps space. I have an Atrix 4G with 16GB on internal storage. 2 GB for apps storage and 10 GB for my use. I have a 32 GB SD card as well. I have over 200 apps to which 75% are for productivity and the other 25% games. Its been over two years now since my purchase and I still have over 1.4 GB of internal storage, 300 MB of apps storage and 12 GB of SD card storage. My phone is my all in one mobile device. (I don't own any other devices.)
All that said, if you are going to be downloading a lot of apps, saving documents, taking pictures, etc. Get the highest Internal memory phone you can afford. Save all your personal stuff to internal memory so if you ever lose or phone gets stolen, they can't get into you files. (Unlike an SD card that they can just remove from the phone and mount on a computer to view the files.) Also, remember that you will never be able to use the maximum storage rated for that device. (Once they install the OS and stock apps.)