6 month old milestones.... HELP

La

My 6 month old is not sitting up unassisted, crawling or showing signs of doing so, isn’t showing any affection, not holding on while being held or carried, laughing, or happily eating purée foods.. I am starting to worry. I see so many other babes nailing milestones and my girl seems a little slower... my heart is breaking... I just want her to be hitting her milestones!