Well, you just mentioned that you keep hitting the same weights and your "transformation is lacking" which I assume means you are not satisfied with how your body looks. If you are happy with your current strength level and physique then there is absolutely no reason to hire a trainer. No shame in this, as not everyone wants to be HUGE and RIPPED or bench 405 pounds. Many just want to be healthy, active, and "look good"
However, if you are NOT happy with your current strength of physique you have 3 options.
Try new stuff for yourself and see if results are different
Have someone else with a proven track record guide you along
Continue with your current program and likely be at the exact same place this time next year.
If you can get a hold of someone with a proven track record of accomplishing what you want to do then what you are really paying for is to "fast forward" your knowledge base and for them to "have made the mistakes for you" so to speak.
Have you ever had one of those "If I only knew then what I know now" moments? How much would it be worth to have someone take you to "from then to now" in 12 weeks instead of 6 years? It can be very frustrating training for a year only to look in the mirror or at your log book and be in essentially the same place... Or worse, 5 years. \
Only YOU can decide if paying someone is worth it TO YOU