bitty baby dilemma

Finley had her 15 month check up today. She is perfectly healthy, but tiny. Avery was the same way, so the doctor didn't give me a big lecture on feeding her or anything (she eats more than her 3 year old sister does most of the time)- he says we just make them little. So, given that fact, I am not necessarily surprised that she is only in the 8th percentile for weight and 9th percentile for height, but I am SHOCKED that she is only 19.0 lbs!I could have sworn that she had hit the magic 20 lb. mark (that is a BIG accomplishment in our house) - I just switched out her infant carrier car seat for her forward facing one YESTERDAY- I was THAT sure!

So, here is my problem. Finley is absolutely LOVING facing forward and now the doctor says that I really should turn her back around. On one hand I am thinking- it is just ONE pound, what would it hurt to keep her forward?! But, on the other hand, if we were to get in an accident and ANYTHING happened to my baby that could have been prevented if I turned her back, I would not be able to forgive myself. So, do I live with a screaming baby for the 8 hour drive to Oregon we are embarking on this evening and maintain peace of mind; OR, do I keep her forward and just pray really hard that we don't get in an accident to make it a more pleasant trip for all?! What to do, what to do?! ARGGG! Just gain some weight already!