Can a girl get pregnant by fingering herself with your ejaculate?

So... I took some Nyquil last night and stayed up watching a movie until I could feel it start to kick in. My eyes started to get heavy, So I got up and stumbled to the bedroom and passed out cold. I'm not sure how long I was asleep, but woke up to my girlfriend riding me looking for a climactic sexy time. It took me a few seconds to realize what was taking place... She was on top of me, and we were having sex. I got into it and we went at it for a couple more minutes, until I felt the urge to explode. I lifted her off of me and finished the job with my hand, which led to a sticky mess all over my chest. She got up and went to the bathroom and I layed there for a minute with the intention of getting up and cleaning myself off but fell back asleep. I woke up again to her wiping of my little soldier's with a cold baby wipe, I got up and cleaned myself off and went back to bed. I'm not sure how much time had passed before I woke up again having to pee, but when I got to the bathroom the door was closed and the light was on. I opend the door and she was naked, standing over a towel that was laying on the floor. Me still feeling groggy, I asked... What are you doing? She said going to the bathroom! I said, over a towel in the middle of the floor? She then sat down on the toilet and proceeded to go to the bathroom, I noticed she had some white stuff on her fingers the she descretly wiped off and then went into the bedroom, I followed. I asked her again what she was doing? She was really defensive about answering and was just him-hawing around the question. She later stated that she was in there playing with herself trying to get off. Now we have been together for over 3 years and she has played with herself numerous times laying next to me in the same bed, So Im not sure why she felt the need to go to the bathroom to do it, let alone lie about it when I asked what she was doing. Maybe the white stuff on her fingers was just lotion and she was really just trying to get off. We have been on the out's lately, we recently broke up and just got back together and I know she thinks im going to leave again. So when I walked in the bathroom and caught her doing whatever she was doing and I saw that white stuff on her fingers, the first thing that popped in my head is that she was using my ejaculate to try and get herself pregnant, So that maybe i'd stay with her. I never asked her if thats what she was really trying to do, So I guess im just curious if that is at all possible. Maybe im just paranoid, who knows. I was thinking about getting some Plan B, crushing it up and putting it in one of her drinks, just to cover my ***. What are your thoughts on all of this?