Filling in the gaps

I have a tendency to write a scene or two and then not write anything for days. The rest of my life interferes, you know? Then, when I get another block of time to write, I assume I'll pick up where I left off, so I reread 8 or 10 pages to get back into the flow. More often than not, I find gaps in the story that I need to fill in.
Sometimes it's minor stuff, places where someone starts to speak but I never told the reader they entered the room, that sort of thing. Other times, it's bigger stuff, like instant character development that should have taken 100 pages worth of trials and tribulations.
I guess that's why this writing process is taking me so long. I need the distance between write and rewrite to even see the gaps.