Thanks for posting on HealthCareMagic.
I am not clear with your description when you mentioned you had negative pregnancy
tests until this past Tuesday (Is it that this past Tuesday, the test became positive?). There are many causes to secondary amenorrhea
(absence of menses) or abnormal menstrual cycle. The first cause is usually pregnancy ( not sure of your last preg. test confirmation). Doing another pregnancy test by dosage of beta HCG in blood is a good way to start. Also a pelvic ultrasound
in order to identify if the uterus is gravid or not is important and also done to rule out other pelvic diseases problems that can cause abnormal menses such as PCOS, abnormal endometrial thickening or endometriosis
, uterine fibroids.
Premature ovarian failure
can also be a cause of the affection.
You need to visit a gynobs for review.
To answer your question and from your description, it will be very unlikely that you got pregnant in October but possible that you could have been pregnant in a later date. Pregnancy signs and symptoms should have been manifesting seriously by now, if you got pregnant in October.
Hope this helps