We can't know an exact percentage on your chances for pregnancy, but anytime you have unprotected sex, you have an increased chance of pregnancy.
The more times you had unprotected sex, the higher your chances of pregnancy.
We know this is a stressful time for you, and you may talk with other women in the Am I Pregnant discussion Group. I hope you find the information below helpful while you determine the cause of your missed/late period, or to help you understand your chances of pregnancy after having unprotected sex (or after a birth control failure).
Late or Missed Period
A normal range for a cycle is 21-35 days ("day 1" is counted as the first day of your period), and many women expect their period to begin on an exact calendar date each month (say, the 15th of each month). Women's cycles, even the most "regular" 28-day among us, cannot use the calendar date as the primary clue that our period is "late", as it is simple math: a "perfect" 28-day cycle that occurs on the 15th one month will occur on the 12th of the next month (in a 30-day month) or on the 11th (in a 31-day month).
Since your period has not begun when you expected it to, please know there are many reasons a woman's period may be "late". Of course, pregnancy is a possibility, but so are other factors: excessive stress, dramatic fluctuation in weight, recent illness, new medication, medical condition or just an "unknown" fluctuation that can happen without cause. The normal fluctuations can occur as our bodies reacting and interacting to the environment around us, and our periods can become irregular for a few cycles, almost "unexpectedly", and this can be perfectly normal. If you are worried about an irregular period or symptoms that have changed, please review the information: How to Know if Your Period is Normal.
Low Chance of Pregnancy Because It was Not My Time to Ovulate....Right?
You do not need to be actively ovulating to become pregnant, as sperm can live inside a woman's body for up to five days when she is fertile; so estimating the time of ovulation after-the-fact (without using a ovulation tracking method) would just be speculation, and not a reliable form of birth control.
Pregnancy Symptoms vs. PMS
The most common symptom of pregnancy is a missed period. The other symptoms of pregnancy usually go unnoticed by women until they are much further-along in the pregnancy (and your period would be a week or two late), as the symptoms of pregnancy and pre-menstrual syndrome (PMS) are identical: acne, feeling of gas/bloating, sore breasts, nausea, headache, backache, irritability, etc. These symptoms are all hormone-related, and this is the reason they are also common before your period. From personal experience: stay away from websites that provide a laundry list of possible pregnancy symptoms! After reading these symptoms enough times, you may begin actually physically experiencing them, but please know that these symptoms are general enough that many daily conditions can cause them (diet, lack of sleep, stress). As much as you would like to know if your symptoms indicate a pregnancy or upcoming period, no one can tell you until the one clear symptom begins: your period, or you have a missed period (in which your next step would be to take a home pregnancy test).
"Only" Tip of Penis, "Only" Lasted a Few Seconds, Rubbed Genitals, No Ejaculation or "Dry" Sex
Only inserting the tip of the penis (or only having sex for a few seconds) is not protection against pregnancy.
When a man "only" inserts the tip of his penis (without a condom) into your vagina, or you "only" have sex for a few seconds, this is still unprotected sex, and is called the "pull out" or withdrawal method. The effectiveness rate is only about 70-80 percent, and occurs when the male withdraws or pulls out his penis before ejaculating.
Please know the pull out/withdrawal method is not "dry sex", as there are fluids exchanged during unprotected intercourse even if the male did not ejaculate. The women's fluids are called vaginal secretions, and are present before she climaxes or orgasms. Every time a man's penis becomes erect, fluid (that you may or may not notice) comes out from the tip of his penis called pre-ejaculatory fluid. This fluid comes out in just a few drops, and may or may not contain sperm. This is called "pre-cum" because it happens at the moment of an erection, and occurs before ejaculation. If you would like more information, read the article on Outercourse: Dry Humping, Dry Sex and Other Sexual Behaviors.
The pull out/inserting tip or just rubbing genitals is also not protection against pregnancy, as there is a very good chance that your male partner ejaculates without meaning to, or, he may not physically physically be able to move away from your vagina quick enough (depending on the position you two are in).
Next Steps
During this stressful waiting time, please check out the EmpowHER "Am I Pregnant" Group and talk with other women, educate yourself on birth control options, talk with your partner about wearing a condom, and make a plan to help decrease your stress (and increase your pregnancy protection) for the future.