I have derm appt - but in mean time I have red bumpy ITCHY rash on part of lower right leg. It's now started on left. What could this be?!

Could be minor... Dermatology is all about appearance. I am guessing it is an erythematous papule ("red bumpy"), which honestly could be an insect bite, or contact dermatitis, both of which are common. However you mention pregnancy; there is a condition called PUPPP: Pruritic urticarial papules and plaques of pregnancy, which are terribly itchy red bumps! See what the dermatologist thinks!