I'm not sure where you're located, Butterfly88, but here in the UK there's a difference between dieticians and nutritionists. Nonetheless, in order to fully register as one or the other, both fields require university degrees.
Nutritionists, however, tend to work within the food industry whereas dieticians work within a clinical/hospital setting. Whilst nutritionists will be knowledgeable, in terms of achieving weight loss, I think you'd be better off visiting a dietician. On the assumption that you doctor is able to, as to be referred to a dietician or seek out one who is in private practice.
Dieticians working in private practice are far less likely to be limited, providing them with far greater freedom over hospital based dieticians, in terms of providing suggestions/alternatives towards maintaining a healthy lifestyle as they won't be as constrained by antiquated Government guidelines.
An example of such antiquation is the continued employment of the BMI scale by UK Government health departments, in order to determine a healthy weight.
However, in the absence of advice from dieticians/nutritionists, despite your previous struggles, you already know some of what you need to in order to begin losing weight, since you know what you should and shouldn’t be eating.
As stated by Trusylver, in order to expand your knowledge further you conduct your own research, whether it be behind the latest application towards improving fitness, losing weight or improving your quality of life.
Most crucially, medical professionals can provide all the advice needed but they can’t achieve your goals for you. That, Butterfly, is something you must take responsibility for.
