I read that there can be an error in negative pregnancy tests if you don't take it in the morning?

Please help. I know this might sound stupid, but I was with a girlfriend about thirteen days ago and she made me ejaculate with her hands. I hadn't ejaculated in a while, so it was a fairly large load. After I was done, I cooled it down with my hand and probably got some semen on it. I got up and grabbed a cloth to wipe off the semen on her leg, but I do not recall washing my hands. We cuddled for near thirty minutes and I'm pretty sure I played with her hair, but then I ended up fingering her on the inside. We have not had penetrative sex and I know that that's nearly impossible for her to be pregnant, but I just need clarification because the mere thought is driving me insane. Her periods have been offset lately and it had normally been on the 25th but changed for the past few months to the 17th and here we are on the 25 and she's experiencing the symptoms and it still hasn't started. She took a pregnancy test about three days ago and it came out negative. I read that there can be error in negative pregnancy tests if you don't take it in the morning. She took it mid-afternoon and she only took one. I don't want to tell her to take another one because that would stress her out even more. I know it's unbelievably illogical why I'm worrying and I guess this is more of a "how do I stop worrying about it?" question because I don't want to put pressure on her any more than I already have. I read stress delays a period. Any suggestions? Words of wisdom? I would appreciate it.