Ditto on Bonnie's response. I, too, was a worried first time mom and panicked that something was wrong! Add to that having autism and aspergers in the family, and you can imagine how much of a mess I became over this "delay".
All for naught, I am glad to say. At 3 years old my late crawler (12 mos), walker (cusp of 14 mos), and talker (don't get me started on that one!) is so fast on her feet that we have a hard time keeping up. She's also an incessant talker with a wicked sense of humor, an extensive vocabulary and song repetoire, and an adorable voice that we sometimes wish was silent (like when her brother is napping!). Literally, she was late with every milestone, both verbal and physical. Come to think of it, even her *teeth* were later than most kids!
Try hard to just enjoy your baby where she is. It's so difficult with all the books, magazines, and web sites telling you what milestone to be expecting this week/month and not even seeing it on the horizon. It will come, and sometimes out of the blue like crawling did for my little blob! Try to resist all the comforts she's grown used to (bouncy chairs, swings, exersaucer, etc) and continue to try tummy time, lay her on her back when she's tuckered from the belly (a minute later, right?), have her sit with toys out of reach, and allow her fuss ~ she'll find her way. My daughter's profile sounds so much like your description of your daughter, and she's proof that yours may suddenly surprise you. Ours surely did!
L.