Pregnant again at 6 week appointment ??

How soon can you find out if you're pregnant ? I'm 5 weeks postpartum but me and my husband have been doing clitoral stimulation but no penetration since the end of week 3. I'm afraid that pre ejaculation got near the vaginal opening from rubbing the area. Is there a way I could be pregnant ? Should I try and take a test or will I find out at the 6 week appointment ? It might be too soon. With my first (also the only child I have right now) I didn't find out I was pregnant until I was already a month into the pregnancy