Need advice!

Went to see the nurse practitioner at 34 weeks and was dilated 1cm and baby was already low and engaged. She said to take it easy, no heavy lifting, no sex. Go to doctor today and she says I'm still 1cm dilated and 75% effaced. She says that I can basically do whatever, go walk around the block or anything. I didn't get a chance to ask her about sex or orgasms because she rushed through the appt! I thought hubby and I could mess around without reaching orgasm but before I knew it I did have an orgasm! I feel awful! I would never forgive myself if something was wrong with my baby bc I did that and sent myself into labor! I'm a FTM so I'm scared now! Please help!! What do you think??