still struggling with a howling puppy?

hi had pup 3 weeks now and am busy crate training her....however after following all the advice i have been given it just is not getting any better...no matter what i try she goes mental when i leave the house and can hear her howling and barking as im coming up the path or leaving. i love her too bits but im at wits end as i feel like im being trapped at home because of a dog who cant be left alone? is 3 weeks still early days or is this a case of separation anxiety??????? just no matter what i try it is def not getting any better?????? puppy is now 11 weeks old and from all the other advice i got it came across that basically it should take a couple of weeks max for her to feel ok to be left alone but nothing?????? please help...i just want her to be happy here and for me to be able to leave the house without any issues!!!!!!