Hi Buzman,
That will actually be a 2 level fusion. The disc space between L3 and L4 is fused, and then the disc space between L4 and L5 is fused. When they refer to L3, 4, and 5 they are referring to the vertebrae. If your doctor is also fusing L5 to S1, that would make it three levels.
I just had L4, L5, and S1 fused, and that is a 2 level fusion. I am 5 weeks post op, and doing pretty well. There are lots of folks on here who just had similar surgery as well, and most are also doing pretty well at this point.
I also have very bad DDD, and L5 and S1 was bone to bone on one side, so I know what kind of pain you have. I can tell you the only pain I have left is specifically from the surgery site. Leg pain is gone, etc. I do have some back aching if I sit too long or stand too long, but I've been able to sit for more then 2 hours at a stretch and can stand about 20 minutes before the ache gets too bad. For 5 weeks post op, that's pretty good. Doctor is okay with my sitting as much as I can tolerate as long as I get up about every 45 minutes and walk around or lie down for a bit.
My surgery took 4 hours. Don't worry, you'll be asleep through all of it

It's definitely harder on those waiting for you to come out of surgery. I tolerate anesthesia pretty well, so my only reaction to surgery that long was a bit of throat congestion that just took some coughing to relieve. For me, the worst part of the first night after surgery was the position they kept me in. They had to keep the bed absolutely flat and would tilt the whole thing to raise my head up a bit. I wanted my head higher but they would not permit it until my brace was put on the next day. I also wanted my head higher for the ice chips they kept giving me instead of a sip of water. Oh well, I survived it, and I cheated a bit with the ice chips, letting them melt so I could sip water through a straw when they weren't looking.
You will be given really good pain meRAB as soon as you wake up. I was given a morphine pump that allowed me to self-administer as I needed it. They program it so you can't OD yourself. It did a wonderful job of keeping the pain under control.
Lots of folks here who can both give you advice and hold your hand through the procedure.
Paula