Re: Two questions...
Welcome to the forum!
As long as you are nursing on demand, not pregnant, and not taking a new form of hormonal contraception, and your baby is producing adequate diaper output and growing and developing at a normal rate, any low supply issues are almost certainly "in your head" and you don't need to take the fenugreek. That being said, the only thing continued fenugreek use will hurt is your wallet, so if you want to keep on taking the pills, go right ahead. You may want to look into buying the bulk fenugreek seed, which is much cheaper (usually about $3-7 for a lb of seed, as opposed to $15-20 for a jar of pills).
Fussy nursing is really normal at this age. It's often due to growth spurts, since there's a big one at around 6 weeks. It's very frustrating, and I think it's one reason why many moms panic at this point and start getting into bottles and pumping, or supplementing with formula. The best things you can do are 1) be patient and allow baby to continue learning how to latch properly and extract milk efficiently, 2) watch her diaper output (any problems with baby's intake will show up in her diapers), and 3) learn to nurse in the side-lying position so that you and baby can both doze during those nighttime nursing sessions. Are you co-sleeping with baby or (shudder) getting up every time she needs to eat?
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"