Cockatiel behavior's

I'm a new owner and pretty sure 4 month old Kiwi is use to us and comfortable enough to start showing his/her true self. But recently started pacing back and forth on the bottom of his cage, chirping letting me know it's time to come out, and will go on until I do...also acts likes he's teething. Even pecking at my neck when he's on my shoulders...Kiwi will chirp and chirp for attention and it's almost like I have a puppy! He comes out several times a day and gets lots of attention...is this because he's getting lots of attention or not enough. Sometimes he will scream for me if I'm out of the room and even come looking for me..it's really something else to see a little Birdy do this. Is this normal? I don't want him to become aggressive. How do I prevent that!?!?