Keeping informed about a job interview, iin?

There was this position I was interested so I sent my resume. She had called me and left a voicemail while I was at work. I called her back and she had asked if I could go in a certain day to get interviewed I wasn't certain yet since I had to work that day. I told her I would let her know today. So I called her cell number and left a voicemail. She hadn't gotten back with me after a few hours and I thought maybe she wanted me to call the business itself while she is there. So then I called and left a message so she would know I was interested. She ended up calling me back and left a voicemail again because I was away from my phone. She told me to just text her since we kept ping ponging through calls. She said that specific day wouldn't work since it was filled but the following week would work. I text her back a few minutes later saying "I will have to let you know if it will work when I get my work schedule which I believe will be tomorrow. She texts back "Thanks for letting me know. I think that it's not necessary to proceed onto the interview now."

I don't think I did anything wrong. I had kept her informed on what was going on. The schedule at the place I get is bi-weekly and hard to get people to fill in for you. I most certainly would prefer not to end up getting fired for looking for another job. What are your thoughts upon this situation?

I was thinking of texting her back that I'll ask for someone to fill in for me that day. Also that I understand that it's really busy there and you only can interview at certain hours.