Dear unsure: Just a couple of clarifications (lots of information to sort through). You had a confirmed ovulation on 10/1 (so a conception would have occurred around here). In that case a urine pregnancy test should give you a correct answer by today--and a blood test on 10/15 would likely have shown some HCG as the blood test detects down as low as 5 units of HCG. Thus, pregnancy seems less likely if you in fact ovulated 10/1.
You mention a 37-38 day cycle, but only an 11 day luteal phase. I'm assuming that you have done some kind of testing (eg progesterone blood levels) or perhaps basal body temperature charting to get the 11 day interval. If this is the case then most assuredly a pregnancy test would be accurate at the time of your anticipated/missed period of 10/13.
If the pregnancy test is correct, the missed period and very erratic bleeding pattern is suggestive of a missed ovulation. Spotting can arise when just modest amounts of the top layer of uterine lining begin to slough off.
There can be MANY causes for missing an ovulation: thyroid problems, pituitary problems, ovarian cysts, physical stressors (eg sudden increases in exercise, crash dieting), emotional stressors (problems with boyfriends/girlfriends, money worries), increased body weight, anorexia, rotating shifts at work, etc.
Bilateral breast tenderness can be a very early sign of pregnancy, appearing as early as two weeks after conception. This is thought to be related to increasing levels of hormones such as estrogen. In a month without an ovulation, not only can a menstrual period be missed, but there can be breast tenderness as well. This is similar to the increased breast tenderness experienced by some women when first taking postmenopausal hormone therapy.
Increased acne and unwanted hair growth may have a hormonal cause as well. Usually this reflects an increased production of male hormones. Most commonly increased male hormones are apparent around ovulation after the LH surge, or if the women has chronic ovarian cysts/non-ovulation (eg "PCOS").
Bottom line, if your natural-for-you cycle does not reset itself after two to three months, or if you develop pelvic pain (eg ovarian cyst), go back to your GYN for follow up. If you are having unprotected sex you could get pregnant before your next natural period arrives--so it is always good to recheck a pregnancy test.
Yours,
Jane