My DD#3 has been walking for about 4 weeks.....so about 17 months she started.....
She only started crawling at 13 months too.

Dont be too concerned....i had given myself a time frame of 18mths...if she wasnt walking or even looking like she was walking then, i was going to go see someone. Deep down i knew this day wouldnt happen, i knew she would walk eventually, but i think OTHER peoples comments often get you in a tither. I had so many 'ohhh arent you worried?' and 'maybe if you get a walker' blah blah...we tried it all....but she sooo wasnt interested in walking....
She also had 2 older sisters to get her things - why the heck would she have to walk - she would just grunt for a toy and one of the girls would run and get it for her.....not silly by any means, rather smart!!!!

Its still early days hun....but i do understand your worry. GIve it time...she will find her way....