My 1 year old daugther had been achieving her milestones well till 9 months. Turned over by 3 months, sat by 7 months, crawled by 8 months and started cruising by 9 months. But she doesnt stand unsupported for more than a minute now. Seems she finds it easier to crawl than walking and immedietely sits down while I train her to walk. Should I be worried?