My skim milk expired on jul 13 & I have been drinking till jul 22. I didn't notice any bad taste. I am 20 weeks pregnant. Will it harm my unborn baby?

Should be fine. Pasteurized and also refrigerated, the milk should be fine the week after the stamped date, as long as it tastes normal. Americans throw away too much edible food just because the stamped date has passed, so it is better to judge the food on a case by case basis. Sometimes, an item may be bad (like moldy bread or soured milk) before the stamped date, and other times still just fine after the date.