I had a semen analysis, need second doctor opinion and more advice?

31 male. No medication. I had a vasectomy 2 years ago and it took roughly 6 months of semen analysis saying 1 or rnms. My urologist had me bring a sample and said I’m sterile. He used a microscope. I wanted a clear lab result so at a year I went and received 2 clear samples!! After the lab spilled 2 of them in transit. I thought about the issues and had 1 more test done last month to make sure and the result was sperm present. So again my urologist had me bring a sample in and he said without a doubt I’m sterile. I asked why the lab said there were sperm and he said sometimes they don’t know what they are looking at. It was quest diagnostics. Now I’m unsure. Can a lab be wrong? Or trust my dr.

In response to my previous question ( http://questiondoctors.com/i-had-a-semen-analysis-not-convinced-lab-analyzed-it-correctly/) of different dr and lab results from vasectomy. It says few sperm observed 1-5hpf from an uncentrifuged specimen.

Sample was qns for concentration