You need to be full-time, with the same preceptor, for at least 12 weeks of births. How many births does your unit do each month? I'm guessing you are not a very busy unit if you were on orientation for 6 months, but only had 5 births. We do about 350-375 births per month, and our low risk L&D orientation is 12 weeks. You get LOTS and LOTS of births in that time. Both vaginal and c-section. You become VERY proficient in labor care (intrapartum), deliveries, and baby care.
Can you be the 2nd assist RN at births in addition to the births you do attend? That will also give you more experience in the immediate birth experience.
It takes a good two years of fulltime L&D nursing to really feel proficient at it. It takes even longer to get proficient in the multitude of high risk complications.
I've been on L&D for 10 1/2 years, and I still learn new things.