I noticed you made a post asking if birth control pills affected the accuracy of a pregnancy test (they don't, by the way, the pregnancy hormone the test looks for is not affected in any way by birth control- sorry to steal the topic and give you an answer but I thought I'd throw it in as well)
Why are you so certain you're pregnant?
Have you been taking your birth control pills as directed? Have you recently been more than 2-3 hours late on a pill or missed a pill, or had you been near when you had intercourse?
If so, then you should take a pregnancy test 10-14 days from when your pregnancy risk was; if the test comes up negative you can test again a week later as a double check for the first test.
Actually, considering your situation, if you are as worried as it seems you are about this, skip the urine tests and go to the doctor to get a blood test; they are (slightly) more accurate than urine tests and if it happens that you are pregnant, thewn you can talk to a medical professional about your options and risks with the medication you're on right then and there.
If you haven't missed pills, though, your risk is almost none and you're over-worrying.
Still, take thest test when you're able to (again, 10-14 days after the risk will yield an accurate result), or better yet, go into the doctor's like I suggested, if you're able to.
I don't know about Accutane or its risks, personally; will these risks during your pregnancy still be present if you discontinue the use of the medicine while you are pregnant? Are you able to discontinue the medication if you are pregnant?
I highly recomend if you are pregnant, either when you get a pregnancy test there or after you have confirmed your pregnancy with a urine test at home, to speak to a gynecologist, if not your other physician as well. If you do not wish to terminate a pregnancy you may have, if you are able to stop taking the Accutane and continue with the pregnancy, find out and be okayed by your doctor. You need to talk to a doctor about all these risks to find out how real most of them are, if they can be prevented, and what your best option is for the pregnancy if the child were at as high of a risk as it sounds to be born with some serious defects; defects which sound like in all honesty, the baby could die either in womb or after birth.
I'm assuming here, please correct me if I'm wrong, that neither you nor your boyfriend are in a position to be able to support this child medically if it lives and has the sort of defects or conditions you've described. Children are expensive as is, but those requiring much more extensive care will be a much, much larger finacial responsibility that often times married couples working two steady jobs cannot front on their own.
I'm not trying to persuade you one way or another, except in the direction os speaking to a doctor about the risks and about your options.
You are not even sure if you are pregnant yet, but if a test does come back positive, please take into consideration what I've said here. Because you are against an abortion for yourself, there could be other options you'll need to discuss with a doctor; but if it comes to it and you need to decide, it also worries me that you've mentioned "I have no other choice than trying to miscarry" - while miscarriages do happen in a number of pregnancies, there is no healthy way to induce a miscarriage in yourself and you could be doing yourself much greater harm by trying for one; so please, find out where you stand now FOR CERTAIN, by a test, and then speak to a doctor about the options you have.