what is the likelihood that I can become pregnant from precum?

you can get pregnant from precum. the only thing i can think of is to get a blood test and im not sure how long you have to wait for that. but have you called your doctor to maybe ask his or her opinion

Yes, from what I've heard, you can get pregnant from pre-cum. I would say that you should just relax, first off. If you are stressed and worrying you might see signs that aren't there, or your period could be delayed from the stress. Do you remember when your last period was? And do you know generally how many days between the first day of your period to the first day of the next? If you do, estimate when your next period will be, and then look up some ways to figure out your fertile days and when you ovulate. Watch for signs of pregnancy, such as nausea, bloating, tender breasts, darkening of your nipples, bad need of urination, etc. Then, about five days before the possible starting date of your next period, take a pregnancy test. You should take several tests over several days, and you can buy them at places like Walmart, Target, etc. You can also take cathrox250's advice and go to the doctor for blood tests, but I would wait until you have a plausible reason to suspect pregnancy (like you have some signs, your period is late, a home test is positive, etc.).

And if you're not pregnant.... use protection next time ;-)

Also, you probably won't have any signs of pregnancy yet, since it has only been a day or two. And depending on the type of home test, it won't show pregnancy until a few days before your missed period.