LESBIAN mom Kim Marshall wants doctors to turn her adopted baby boy into a baby girl with a full-blown sex change -- now! And if somebody, somewhere, doesn't bring pressure to bear on the woman's plans, toddling 2-year-old Tommy Marshall will soon be toddling "Tammy." "Looking back on it, I never should have adopted a boy, but he was all that was available and I took what I could get because I was desperate," says Marshall, whose significant other, Rosemary Johnson, says she "hasn't been real happy with a boy," either. "It's not that Tommy isn't a sweet kid --...