Baby is almost 4 weeks old and only wants the boob

First time mom and it's been rough. My baby is fussy and nothing seems to calm her down.. except nursing..it ALWAYS calms her. She seems content in the mamaroo for literally a few min then starts crying. Even when I rock her she fights sleep. It take a bit of time till she falls asleep, unless she is exhausted. I don't think it's gas because I've given her gas drops and even gripe water and don't really notice a difference.

If giving her the boob is what really only calms her, do I just always give it to her? This might be a dumb question, but again I'm a FTM..

I seriously can't get anything done because the moment I put her down she just starts crying and my only resort is to nurse her for instant relief or rock her to sleep if I feel she should sleep. Anyone else in the same boat or experienced the same thing? How long did it last for you?