One more thing that I found helpful: There's a guy on the Starting Strength Forum named Jordan Feigenbaum. He's really a lot smarter about nutrition than most meathead types including Rippetoe himself. And he's a lot smarter about women and weight lifting than most people are, including the knuckleheads arguing stupid stuff here. I think he really understands that the same stuff that works for men doesn't work the same way for women.
Anyway, this is his forum.
And he did a reddit AMA recently that was pretty interesting.
Jordan Feigenbaum: AMA on Starting Strength, Nutrition, Etc. : Fitness
If you scroll way down he has some useful stuff about how women's bodies work a little differently. Here's the quote:
I have found this to be true for me as well. I need more "something" to progress. It's not always clear what it is. More volume? Yeah, I think so because I have never felt like the strength "sticks" without more volume. Sets of 3? Yeah, that worked for a while but so has lots of volume at lower weights. I can do sets of 5 or 10 on what I could only do on sets of 3 before, but hell if I can automatically lift heavier even if I can do more reps. So maybe I need both more weight and more volume. More "something". I'm always looking for it.
I'd keep doing the negatives, you'll get one very soon. Then do singles at the end of the workouts. Eventually you'll be busting out multiple reps. Females, due to both the acute and chronic effects of decreased testosterone as compared to men, do not get as robust a response from a set of 5 reps. Moreover, they cannot recruit the motor units in the same fashion a man can to perform a true 1 rep max. This allows women to do sets of 3 or 5 much closer to their "1 rep max" than a man can, because women cannot produce a true 1RM. Because woman can do this, they tend to respond better to higher intensity training, i.e. heavier weights (sets of 3's) with approximately the same volume as men (15 total reps) OR more volume (8 sets of 3 reps) at the same intensity they'd do for 3 sets of 5 reps. Inn talking to multiple other coaches, we've all had the same experience, i.e. women need more "something" to progress. Usually this results in training with heavier weights and lower reps, vs. just turning you into a volume junkie since your sex's CNS tends to respond better to increased loading vs. just increasing the volume.
Female, 5'3", 48, Starting weight: 163lbs. Current weight: 135.
Starting squat: 45lbs. Current squat: 145 x 4.