My daughter was easy to put to bed for the first 6 months or so as well so I can relate : ) Is your daughter sleeping in the room with you or her own? Is she self-soothing and putting herself to sleep or are you holding her until she falls asleep? Do you use a fan or other sort of "white noise" near her to block out any noises she may be hearing?
Babies as they get a little older become more aware of their surroundings and respond in kind. If they're in the same room with you or you're holding them until they fall asleep they may not want to lose your company. If there's anything going on around them like the TV, people talking, noise from outside their window, etc., they may not want to "miss out" on the activities and will refuse to nurse, rub their eyes and get fussy in an effort to stay away.
I used a "relax and calm down" routine. Start with a warm bath, a rub down with lotion, softly talking to her as you dress and nurse her for bed, dimming the lights, placing her in her room with a fan nearby, close her door and leave her to self-sooth herself to sleep. She may cry a bit, but what we think is hours is usually just a couple of minutes in reality. If she cries 5 minutes or longer you can go in, leave the lights off, and her in her crib, talk to her softly again, rub her tummy or leg a little, say goodnight and gently leave the room again. You may need to do this a few (or more) times if she continues to cry (wait and don't rush in right away or she'll catch on real quick that you'll come running when she cries) and as she gradually gets used to her routine and knows that she's not getting up she should develop her sleep pattern again.
Hope this helps<3