Well, that's good! And that's what it sounded like, too. You still face a lot of challenges, having a baby with someone who was (as recently as a month or so ago) "high all the time,' and you being unwilling to ask him to shape up because he has a bad temper. But at least this worry is no longer on your plate.
I hope he'll do for his child what he wouldn't go for you. Good luck to you, and congratulations.
Baby was born yesterday and is my boyfriends! Looks just like him - she’s without a doubt his daughter!
Given everything you have said, I'd say that you should be cautiously optimistic that you were probably a couple or a few days pregnant by the time of the unfortunate event on the 30th.
I don't know why the same people told you on January 15 that your baby is due September 17 and that your GA was 4 weeks 2 days. But since it's pretty hard to measure an embryo early in the fourth week, and since the due date of September 17 has been confirmed more than once (by ultrasound each time, right?), it's more possible that the 4 w 2 d was slightly in error than that the due date of September 17 is where the error lies. A September 17 due date suggests conception on December 26.
Taking the December 26 from your ultrasound(s), even if you figure that number is based on someone with 28-day cycles and add a day or two to account for your longer cycles, it would still only move the date to December 28, not December 30.
Plan B gets less effective the further from the sex you're trying to correct for. That means the Plan B not working doesn't really suggest anything about when you ovulated.
Having had a lot of sex with your boyfriend doesn't count as much as it seems like it would, because 2-3 times a day for ten days or more will reduce his sperm count. In the past, doctors would even caution people to only have sex every other day or even every third day if they wanted to get pregnant, but doctors don't say that as much as they used to. They do say that sex before ovulation is a better idea than sex after ovulation if you want to get pregnant, but I think that is because they don't want you to miss ovulation by accidentally miscalculating when it will be. Anyway, luckily it only takes one sperm. :) Is the baby a girl, by the way? It so that would also tend to bolster (very slightly) the idea that your boyfriend is the dad. (Not that a boy would mean he isn't, though.)
After this length of time, it's not that easy to tell where the counts from doctors came from (ultrasounds or last period or something else), and if later ones came from merely copying the last date into the file and not judging independently from the info on the newest ultrasound. So you do need to be ready with a plan in case worst comes to worst and the baby is not from your boyfriend. (With a boyfriend who has anger problems, it had better be a good plan.) It doesn't quite sound like your worst fears have been realized -- it sounds (to most extent) like your boyfriend is the dad. But when you have a boyfriend who has a temper, you have to be safe, your safety and your child's are number one. That includes having to tiptoe around him out of fear of his temper, and keeping from him the bad things that happened to you because you're afraid he will be mad.
OK, well, first of all, I suppose you know that being raped is not your fault, and is nothing you should be ashamed of yourself about (though the guy should be ashamed, if not arrested).
Let's look at some your info.
What estimated due date (calendar date, not the weeks count) did they give you on January 15 when you had your first ultrasound? Did you have a subsequent (but still early) ultrasound that also said the same estimated due date?
Also, taking Plan B "within three days" -- does that mean more than 48 hours but less than 72 hours?
Finally, what consequences do you think you'll face if it turns out your fears are realized and the baby came from the sex with the guy who forced himself on you? Have you been telling your boyfriend all along that the baby is his, and he will not find that forgivable even if he is made to understand that you didn't want to tell him about the rape?