See some yellowing tips???

The yellowing tips are a sign that they're getting too many nutes - that's a slight nute burn you're seeing... and an excellent example of why you start an auto off with 1/4-12 strength nutes when you first introduce them. She's not liking them very much so I would give her plain pH'd water for the next week and then try to introduce the nutes again. She's a strong looking lady and I don't think you're going to have much of a problem with her! Be aware that she might be going into pre-flower within the next 2 weeks so when you give her nutes again, you can also add a small amount of bloom nutes to help her along setting bud sites... You wondered about LST .. I'm thinking you should definitely try it since she looks like she's going to be very bushy, very leafy ... you're going to want to help her get light to the bud sites... Good luck - looks great!