I am so sorry to hear about your bird. Please don't feel bad - it unfortunately happens. One of my friends had a budgie for only a few months and someone I met in my local pet shop had one for 3 weeks before it died. It is hard when it is your first bird, but your little pal taught you a lot and it looks like you had a lovely bond with her.
When you feel ready for another budgie / budgies you will know. I left it 8 months after my first budgie died. Now I have 2 and they are fab. But I never forget the first one - she introduced to the wonder and joy of budgies.
My flock: RIP Cheeky 'Sweet Cheeks' 4th April 2013 (pictured)
Jingle and Bells, born September 2013 and still alive and chirping!