How do I stop puppy barking when I leave the room?

Hi,

Meg is now 16 weeks and is a rescue pup. I've had her a month now.

She struggles when I'm not in the room but still in the house/garden. She's fine if I leave the house completely through the front door (but not into the garden). I know because I go next door to check!

If she hears my alarm in the morning she barks. If I go into the garden she barks. And this barking is not just one or two yaps, it's constant for about 10 - 15 minutes. She almost gets herself into a state.

I don't go to her until she's quiet and I've tried slowly increasing my departure, going back in and then leaving again - slowly increasing the time I leave her....it hasn't improved.

It's especially bad in the morning when she starts barking when she hears the alarm going off, or if I go into the garden and leave her in her crate.

She settles in her crate nicely and will stay in with the door open while I'm in the room (goes to sleep)

Any suggestions would be very welcome!