Nub theory wrong?

I know it’s just for fun and not 100% but has anyone had the Ramzi theory, nub and skull theory right? And has anyone been told it was one gender for all of the theory’s but turned out to be the opposite gender? I’m only 13 weeks and my scans are kinda weird and blurry so it’s hard to tell. Some are saying girl and some are saying boy. I do not care I already have 2 boys and 2 girls so this is the tie breaker and be believe as long as baby’s healthy! I’m just curious