At 4 weeks we used the bouncer alot for most of her day sleeps as we also had probs, that way I could just rock it with my foot while resting on the couch and once asleep I didn't have to move her. Also the pram, just pushing it back and forth.
At 4 weeks I really wouldn't worry bout "bad habits" its easier just to find what works and go with it, especially for the first 3 months.
Good luck!