I have looked over your code and am wondering if your LCD is displaying anything at all. From the 44780 user guide the following is their recommended (required, maybe?) initialization procedure:
1) After power up wait 15 milliseconds.
2) Send 30h and wait 4.1 milliseconds
3) Send 30h again and wait 100 microseconds
4) Send 30h again and now start checking ready.
5) Send 3Ch for for 8-bit, 1 line, 5x7
6) Send 08h Display OFF
7) Send 01h Display ON
8) Send 06h for right shift entry mode

Now you can send all the data you wish.

Using the above sequence I have never had a problem with LCD's. You can probably abbreviate the procedure but this is what is called for to set up my Optrex DMC-16230 display using the HD44870 controller.

Hal