From my medical background, I can answer some of your concerns. I see that you are pregnant and due to have a baby soon. About one half to one third of all women have a problem with urinary Incontinence and Bladder control. It can be caused by the baby leaning on the bladder, and cause some seepage. If you are wearing white panties, it is easier to see the COLOR of the wetness. Is it clear or slightly pale yellow? If it is in the front area, it is probably urine. In the crotch area, it could be a discharge, which ranges from clear, white, yellow or brown. If your urine has a strong odor and is dark colored, or contains blood (is pink/red), it is a sign of infection. Discharges that smell, itch, burn, or are colored are also a sign of something going on down there. See your doctor if any of those symptoms exist. It is normal for a women to have a clear discharge, often caused by activity and hormones or ovulation.
Certain factors can cause you to leak. AGE, (older women), pregnancy, hormone changes, activity and exercise, laughing, sneezing, coughing or even hugging someone. As a woman gets older, her muscles are weakened and it can be caused by weak vaginal/urinary muscles.
If it is more than a little leakage, you can be prescribed medication for it, but being that you are pregnant, I am not sure what the doctor will suggest. The condition of bladder leakage normally goes away after the post partum phase, when your muscles begin to come back to normal.
Hope that this helps.