Is this dangerous?

Me and my boyfriend have been doing oral sex lately, we both don't want to have vaginal sex for a long time. But I got nervous thinking about it after awhile. I usually do him, by giving him a blowjob and or hand job. Or he does me first, fingering and cunninglus, and than we switch off a lot throughout the day by taking turns. But after he orgasms I grab him a ton of tissues and he cleans up, is that unsafe? What if some of it gets onto his hand, because he usally does me next, which involves fingering me in my turn. I'm afraid what could happen if it got on his finger and he fingered me, pregnancy? Am I over thinking it? Please respond!