Why am I experiencing blood, uneasiness, frequent urination?

It is impossible to diagnose your pregnancy under the circumstances without a pregnancy test and a checkup. A gynaecologist specialises in women's reproductive health and can provide the proper medical advice and treatment.
 

Yes, you can get pregnant having sex 3-4 days after your period. Sperm can live inside your body for up to 5 days..and if you ovulate earlier than usual, say, in a 25-day cycle, the chances of pregnancy are even higher. Always use contraception unless you're trying to conceive.

You might encounter a yeast infection. Yeast is a microorganism that can grow excessively and cause itching and white discharge in the vagina. It is because they have sometimes taken antibiotics or wear tight clothes. You can indeed use the over-the-counter cream for yeast infections. Hence, wearing cotton underwear and the absence of scented products near the vulva are among the best ways to help ladies prevent yeast infections in the future.

If 11 days have passed since the date of the expected period but you have done the love deeds, it is a good idea to check whether you are pregnant. Irregular periods and being sexually active are among the most common signs of pregnancy. You can be pregnant if you haven't used a condom while you have sex. Pregnancy tests that you can do at home are an accurate method to find out. The tests reveal pregnancy hormones in your urine.

If the intercourse was rough, it could just be irritation making itself known, or possibly even a small tear in your partner’s vaginal wall. Look out for any sign that it might have been more than that, like if there’s pain at all beyond normal discomfort during sex, or weird discharge afterward. 

The light and brown bleeding you had after swallowing an OCP pill a week later following intercourse is not indicative of pregnancy. It is one of the common side effects related to your body due to hormonal changes which you experience when utilizing pills. However, one is advised to seek advice from their gynecologist in case they have any doubt or fear.

Emergency contraceptive pills, like the one you took.. can cause changes in the menstrual cycle including lighter or irregular bleeding. The bleeding you are experiencing could be due to the pill or your regular period. It's important to take a pregnancy test if you have concerns about pregnancy.

The Last Menstrual Period (LMP) calculates gestation from the start of your last period, while gestational age by Biparietal Diameter (BPD) or Femur Length (FL) measures the baby's size. The difference in weeks might be due to variations in fetal growth rates. Your obstetrician can provide more insight and guidance based on these measurements. It's always best to consult them for a clearer understanding of your pregnancy progress.