Most people only have orgasms with actual intercourse or clitoral stimulation. Some women will orgasm out of the blue. This may be more common in pregnancy due to increased blood flow to the vagina and clitoris. Sometimes, with a prior history of miscarriage, especially if there is cramping or spotting in the current pregnancy, we recommend avoiding sex. Your doctor will know best given your individual situation.
Blood pressure tends to drop in pregnancy.
As long as you don't feel dizzy or overly tired, then it is not a problem. I'm carrying kind of high and find it hard to breathe at times. I'm seven months pregnant. This is a very, very common complaint. Most women notice it when they are trying to sleep.