14 week old sleeping issues

I have a 14.5week old and shes very difficult to out down to sleep. She doesn’t fall asleep independently and I have to rock her or feed her to sleep. It takes forever for her to fall asleep. We have a solid bedtime routine. Example tonight its been 3 hrs ive been struggling to make her sleep. She falls asleep for 10mins and wales up over and over and over. Shes clean, fed and comfortable. Im at a point where I just let her fuss and cry to sleep cause I cannot spend another hour in a dark room rocking her. You think its okay to let her fuss/cry to sleep at 14wks? Of course if she becomes hysterical I will go in there but it’s absolutely crazy that it takes 3+hrs for her to sleep.