OK. Understandable.

I do have other ideas/options! 

1) My character could be a very cynical, sarcastic, bitter, and skeptical person due to abuse in the past. Very cranky, and seems to never smile or laugh. But she is very intelligent, and would be a reliable friend even if she won't admit any of her feelings honestly. She is very tough and is not afraid to pick a fight, may have a bit of a foul mouth though. Very much a loner. She would quite scared of the future (again she won't admit it), and hates her past. 
She would also be the drag along archetype. She wouldn't want to take any part of the Doctor's journeys because it doesn't make sense to her, but she can't go home because something happened to her world and time (she managed to get to the TARDIS safely before she died/had something happen to her like everyone else), so it's not safe for her to go back. She only agrees to help the Doctor in order to get back home faster. 

2) My character could be a shy and meek character, who seems to be afraid of everything, including her own shadow, due to bullying in her past. She doesn't speak much, and has social anxiety. Very polite, and kind, but also serious. Tends to be made fun of and made the butt of many jokes. She also is afraid of following her passions and doing what she wants instead of doing what is considered 'correct' in social context (talking career wise. Becoming a doctor instead of a singer, that kind of situation). However, she would also prove to be very reliable and a brave person if any of her friends are in need of help. The phrase 'Beware the quiet ones' would apply to this character. If a certain emotional button is pressed, she will go on an angry rant and let her real emotions out. 
She would be with the Doctor because something happened to a childhood friend of hers (She doesn't have very many friends), and wants to help her friend, even if it means leaving her home and her comfort zone.

3) This character would be a relatively calm person who just goes to the beat of her own rhythm. She's very creative, and has simple tastes. She acts like an old woman, but that means that she's wise in some aspects, more in the philosophical, and situational instead of science or biological like the last two. She has a few friends (that's more than the last two combined) and very few enemies. Cross her, and she could be very manipulative and sly. She may look out for herself, but that doesn't mean she won't look out for her friends. 
She could be facing writers' block as of late. The adventures with the Doctor would help her come up with a new story to write.

4) This character would be most synonymous to Dr. Jekyll and Mr. Hyde. She has two personalities. She is two people as one (This could be just a coping mechanism, or this could be caused by an alien). Her normal self is just the average Jane who just wants her life to be normal. She tries to be normal and fit in, but her other personality doesn't allow that. Her other personality is random, chaotic, and can be quite destructive, and quite often claims that she will take over the world one day ((for comedy)).
If the other personality is an alien, then the Doctor could try and find a way to 'cure' my character.