Welcome to the board. You are still very early in recovery. This surgery takes a lot out of you and it takes many months for energy levels to return to normal.
Almost everyone that posts on the board has been surprised at the general lack of energy they felt for quite some time. Usually twelve weeks or around then there is some progress. But for many people it takes a year to begin to forget you had surgery.
If you are having nerve pain, it can take longer than six months for the pain to resolve...and of course, depending on how long the nerve was compressed, it may never completely resolve. Doctors will say that after one year, if the pain is still there, it is likely to be permanent...but I have found that I am still seeing changes and my 3 level fusion was in June of 2010.
Sometimes people don't realize that it takes a lot of energy to grow new bone cells. It is very important to rest. That and taking many short walks are your most important activities, especially during the first three months.
I quickly learned, once I was allowed to drive, that I no longer could do a string of errands, shopping, etc. in one trip. By the time I showered, dressed, etc. I was almost ready for a nap. By the time I did one errand, I was ready to rest. So I learned to make just one appointment per day...like if I had PT, I didn't try to do much else that day.
Don't be discouraged. This is all very normal. You will find that a great deal of patience is required to get through recovery successfully!