Character Descriptions & Past/Present Scenes

I'm working on developing my characters without actually describing them in a block of sentences.  (Ignore the red words until you get to my explanation below.)

As she gazed at the necklace, her mind wandered back to her 9th grade introductory English class.  

"Who is Alexis Heston?" She had asked herself out loud while reading the teachers' assignment.  

"Who am I?" she (had?) repeated, bewildered by the question itself.

"Mom, who am I?" she (had?) asked, hopeful for a hint from the person who knew her best.

"Alexis, you have to answer that one on your own" she (or "her mother"?) replied with a chuckle.  

"And its not an easy answer" her mother (or "she") continued. "Answering that question requires introspection and self-awareness.  That means looking inside of yourself to see what's really important to you and what you want your life to mean."

Over the years, this conversation had replayed in her head often.  It seemed to pop up whenever she had those strange, uncontrollable feelings that came from nowhere and disappeared before she could identify their origin. 

Now, as she stood in the mirror, admiring the jewelry, that same question returned to her mind.  

"Who am I?" she asked herself.  She ran her fingers over the necklace and wondered if it truly "fit her well" as the salesgirl had suggested.  The piece was both heavy and delicate all at the same time.  In that way, it did remind her of herself: hard on the outside but delicate and very easily broken.  

Hopefully, from this passage you get some preliminary information about Alexis and realize that you'll learn more about her as the novel progresses.  Yes...No...Maybe?  

I also have some concerns about accurately portraying the past when its being examined in the present. Here, I used "had" to show that Alexis was thinking about the past right now.  But then, I wasn't sure if I needed to continue with the "hads" to let the reader know this was still the past scene.  When her thoughts returned to the present, I removed the "had" to alert the reader she was back in the present scene. I also used the line "Now, as she stood in the mirror," to let the reader know that the past scene was over. 

Did that come across well?  Are the sentences clear enough that the reader understands which part happened in the past and which part is occurring right now?  

I'm also concerned about when to move from using the character's name to using the pronoun.  Its difficult sometimes to make it clear to whom you are referring when both characters are the same gender.  

Its all basic stuff I know, but hey...give me a break, I'm just starting out.  :) 

Thanks for any feedback.