Paternity labs

So my boyfriend before we got together had a one night stand with a family friend on May 16th and had her last period April 27th and 28th and in July she took a pregnancy test and she was pregnant. She is currently 19 weeks and 3 days. She didn't know who the father was she kept going between my boyfriend and some dude named Nick. So we took a prenatal test with her and my boyfriend and he matched 12 of the matches they tested for. I was wondering of that is enough to make him the father or if the test results were false and not trust worthy. Another thing is he tried to have a kid with his ex 11 times and nothing happened and he hasn't gotten me pregnant either since getting together. I know different women conceive faster than others but what are.your guys thoughts?

Update We did a dna test with DDC and it did turn out that my boyfriend is the father.