Sleep advice

Y'all, I'm desperate. My precious little baby won't sleep. Well, let me rephrase- she WILL sleep, but she won't GO to sleep. Does that make sense? See, once she goes to sleep at night, she will sleep for 8 hours at night, but getting her to sleep is next to impossible! We loosely use the Babywise method (mainly the eat, awake, sleep part) and that worked for getting her days and nights un-mixed up (thank you NICU for that)- but poor baby just won't nap during the day and by the time it's bed time, she is so overtired that NOTHING works. We swaddle, keep the room dark, have a music seahorse in her bed, give her the paci, rock, pat her back....everything the books say to do, but she just won't go to sleep! I am so desperate, I am actually asking for internet advice (other than trusty google- swear I am writing a book called "Parenting by Google"). This is new to us, even though we have a 3 year old and are clearly not first time parents! Although, I feel like I should be in remedial baby 101 or something...I have forgotten EVERYTHING babies do! JP never needed to be rocked, or anything- we did swaddle him and he took a pacifier and we let him cry it out once or twice and he was fine. The child always slept, we were spoiled, I know, but now it's making poor Addison suffer because  she's so tired! I guess I need to suck it up and let her cry it out, but for some reason, it's much harder with this baby than the first one! So help! Please!!!! Leave me some advice!