A question of character

One mistake I've made with this project is that I didn't write biographies for Sue and Jackie. Now, I find myself feeling that I don't know my characters. I promise, the very next project, I will write biographies of all the major characters in it before I write a word of the first draft.
Whenever I've written biographies, they have paid dividends when I began the actual writing. You get a sense of who they are and how they think. For me, a sign that I've got a living, breathing character is when I tell myself : "No, he wouldn't do that," or "That goes against her principles." That sounds like a nuisance, because you want to try and follow the plot. But it's really a blessing. I've found, over the years, that the best stories, the ones which the reader WANTS to read (or the audience WANT to see) are the ones where the characters are solid and real. Better to adjust your plot - perhaps have something or someone force the character to carry out the action reluctantly.
Over the years, I've created a blank form which would be the envy of Scotland Yard. It has spaces for the charcaters' hair colour, daily newspaper and voting tendencies. I can write down the character's life story from birth to the present day, inventing such milestones as the character's first job, first romantic encounters, and wedding anniversary. There's even a space for the character's pets. I also have spaces for Person Closest To and Spouse/Partner (in case they are not one and the same).
This blank form is an adaptation from similar forms found in Stella Whitelaw's "Writing a synopsis that sells" and Donna Levin's "Get that novel started". I've also found a useful character creation checklist on Holly Lisle's website:
http://hollylisle.com/
The reason I didn't do it this time (and lots of other times, when I should have known better) was because it seemed like a chore. It always does. I seem to have been
planning, planning, planning projects for 20-odd years and then abandoning them. I want to write again, I want to feel like a storyteller.
Before I found out about character biographies, I just used to sit down and write. At first, my characters bore strong resemblances to my favourite television characters. Later, as I grew more sophisticated, I just used real people, without any thought of disguising them. Until the real people (the ones I cared about)started to get annoyed.
The problem now is, I want to abandon this stage play and go onto the next project.
The one where I'll plan it all beforehand, and this time do it correctly.
But I've made myself a promise. I'm going to finish this play, however badly it turns out. Whatever is wrong in the first draft, I can make better in the next.