Looks like you are overstressing here mate, took a look into ur diary, don't see no burnt tips, the red could be genetic/too close light/low phosphorous. Considere these 3.
You seem to be overwatering, try getting a wood stick and place it in the pot, whenever you think its watering time, lift the stick, check if there is humidity inside the soil and then if theres none or too little you water. Me personally i use the leaves method, you water, leaves go down, leaves go up and stay up untill they start going down due to thirst, ur gonna want to water them as soon as they start going down.(beware as sometimes near the end of the light cycles some strains tend to get droopy leaves in preparation for the dark period, sometimes its just a phase, other times they do that for a long time.
Your soil seems like it could be very light, by this point the plant would start requesting for nutes if its the case, as it seems, so giving it a tiny portion of grow nutes could let you know if that's what she wants or not.
Check ur ph if u can 6.5 will be optimal.
Note: let ur soil cycle from dry to wet to dry and etc... my pots tend to get 95% dry before they are watered again as while there is humidity the roots are searching for that water and will chase it to the furthest regions of the pot if those are the only wet places, just dont let her get so thirst that she dies but better underwatered than overwatered. Good luck mate. Anything just shoot me a DM or if dms still not working drop a comment on my profile.