My Yorky is 5 months old she keeps knotting we bath her every 2/3 weeks any help

I have an 8 month old yorkie and I bath her once a week and brush her everyday. I find that this helps her from getting mated and knots. I also found that if you use the professional doggy shampoo and conditioner that there are fewer knots. I also use a professional spray to put on her before brushing each day that helps to detangle. Works wonders and smells great!! Hope this helps. Shirl :D