this is really only the beginning period for crawling-some don't crawl until 9months, some even more than that. i wouldn't worry that she isn't doing it yet, but she is trying and that's a good sign. she's getting frustrated because she obviously really wants to move but doesn't know how yet. just keep giving her floor time, but do it in little bits so that she doesn't get sick of it or too bored. also, i found a good exercise with my boys was to lay baby on back, (gently) grab around shin/calf of each leg and gently push the legs up to totally bent position and then stretch them out. continue this gently. baby usually thinks this is very funny and a great game, but it's also helping to strengthen their legs. another thing to do is get behind bubs while bubs is on belly and show bubs how to move legs by moving them with your hands, while bubs pulls along with arms. also, in the same position (behind bubs) push your hands against the soles of her feet with her legs bent under her one at a time. it's a reflex for her to push off your hands, although i think this is supposed to be started earlier on (3 months?)-she may have grown out of it already.
usually bubs will get up on all 4's and rock back and forth as if she is going to take off, RIGHT before actual crawling. is she doing this yet?
anyway, this is my advice from my experiences, but just don't push her to grow up too fast, she's only little for a short while! smile
hope i've helped!
...anyway, "storm"-what a great name!!! grin
3 boy bundles of joy under 6, qld