18, worried I'm pregnant

I am currently 18 years old have have been sexually active with the same guy for two years (he is currently 20). I am not on the pill, but we ALWAYS use a condom, and we check frequently to make sure it hasn't slipped off or broken. He also never ejaculates inside of me even though we do use condoms every time, just to be doubly safe. We have not had an accident or anything with the condom. The amount we have sex varies. Sometimes it's a few times a week and sometimes it's only a few times a month.

For the last two months my period has been between a week and two weeks late, but I always get it in the end and it is always my usual seven day heavy flow. The first month it was late I took a pregnancy test and it was negative. I did the same the second month with the same result. I also can't tell when I'm ovulating anymore since I have been so irregular.

This month, my period once again failed to come on time. I have begun to get very bloated and my breasts have been sore, very much like right before I get my period. Of course, being the overly anxious person I am, I'm once again worried. I am planning on getting on the pill very soon to stop all this worry.

I should probably also mention that I am very thin. I don't even weigh 100 pounds and I am always stressed and anxious. I also drink tons of caffeine and don't always eat the healthiest, so all of that causes irregular periods as well.

So my question is this:

Should I take another pregnancy test, or is this once again nothing to worry about?

What are the chances that I am?

I am a worry well myself. Which is how I ended up on this forum. The power of the worried mind can be an evil thing. Sex and pregnancy is normal. Your body wants to get pregnant. The more chemistry you and your lover have the more your body will produce hormones to help you get pregnant. The only way to prevent it is to take precaution. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

As for your question. Dont waste your money. you cannot get a reliable result from urine tests until you have missed your period. Your period can also be late due to your ovulation cycle. If you ovulate late your period will be late. Try to relax and wait it out. 10 days of missed period you can start to worry.

And yes you are ovulating. 18 to 23 is the baby making years, beware. take care and be patient