Are you sure it is an Angel Trumpet and not a Trumpet Vine? I have three trumpet vines I wish I had never planted! They are terribly invasive and grow all over the place. They tend to grow tall before flowering. They also cling onto walls, fences or house columns with little tendrils so that when you come to cut them down it pulls all the paint or plaster away with it. If yours is a trumpet vine planted in a shady area it will grow to the light before flowering, it may flower in the shade but not much.