Let me lay something out for you.
This is coming from a good looking guy who has a "great" facebook profile. I crafted it as uniquely as possible...pictures of me modeling, baby pictures, traveling etc. I've done all types of experiments on Facebook and the thing I'm going to tell you and anyone else reading this is to never use facebook to ask a woman out. You can add random people as friends and if they accept that's cool but leave it at that. You can have short conversations with women and that's as far as you will get. Don't ask women out over facebook.
Do it in person.
Whether she has low interest level or not you will only find out if you have the balls to ask her out face to face in person.
--Gentle persistence is the key --
If she tells you to add her on facebook that's basically a rejection. Don't fall for it!!!
Facebook, twitter, instagram are all bullsh!t. It's all a ploy to get attention that most people lack so don't get sucked into it. This is what most people do on facebook....they update there "status's" everyday, post pictures of food, there kids, getting married, random bull**** and videos. Again never ask anyone out over facebook. Even pictures that people post you have to look at them very carefully. Women will post pictures from angles hiding there ugliness.
If it were me I would just add her for the fAck of it just to boost up my friends count and that's it. I have a facebook account as well just to have an online presence but what I'm doing now is trying to max out my friends list and all I use it for is to watch videos that people post up and stay up to date with what's hip or what are the new trends that everyone is following for example :- ALS Ice bucket challenge. It's a good way to stay in tune with what's going on in the world but other than that it serves no purpose.