Don’t stress out! You may be, you may not be. Let things turn out the way that they are supposed to. If you are, there is LOTS of help and support on this site. It helps a tremendous amount.
If you are already pregnant, then there is no way of stopping it unless you were to choose an abortion… which if you’re leaning towards that, I advise you to REALLY THINK about the cons, which are higher than the pros.
Also, if you’ve had a miscarriage before, I read in “What to Expect When You’re Expecting” that your risks are slightly decreased for the second pregnancy in a normal, low-risk pregnancy. So, just because you’ve had one before doesn’t mean that you are going to now!
One more piece of advice… if you’re not pregnant, learn from your mistakes! It seems like you’ve made this mistake over before… but have more respect for yourself and wait for the right man that you love!