It's completely unhelpful to throw around made-up statistics like how "9 times out of 10" it's about trying to gain some advantage. There's simply no evidence for that, and rather a lot more evidence that gender dysphoria is genuine, and beneficial to diagnose and accept.
Setting that aside, the definition of transgender is, I think, helpfully outlined in the links above. Generally, but not always, transsexual also might say something about medical interventions.
What I'd like to add is that it is, at the very least, problematic to attach too much weight in the definition to whether or not a trans person has had surgery, or any other direct medical intervention. For example, the waiting list for even a first consultation at an NHS Gender Identity Clinic, while it varies regionally, easily exceeds three years in most places. Following that first consultation, there can still be a significant delay for diagnosis. And remember that by the time someone has taken the decision even to start this process, they are already sure within themselves that they need at least that first consultation. After that, there can of course be a long delay before being approved for treatment, be it hormonal or a surgical procedure. It's possible to seek treatment via private routes of course, but in that case you'd still have the barrier of potentially large expenses to pay for any operations.
None of this is particularly unique to transgender care -- the NHS is overstretched in multiple ways, especially related to issues that intersect with mental health -- but it still raises the question about what to do in the interim. Also, all of this is technically a private matter anyway. It's up to an individual what they share about any medical procedures they've had or are planning to have. How we then interact with those around us is a matter about who we are as a person, not about what changes to our bodies have taken place.
All of which is to say that being transgender implies nothing about medical procedures. Brianna Ghey was transgender.
// Scotland's proposed bill aimed to allow people to change gender from sixteen //
Just to answer this point specifically, the bill aimed to lower the age at which one could *legally* change gender, by obtaining a gender recognition certificate. Again, it's hardly specific to transgender people, but the law is often slow to catch up on these sorts of thing. A piece of paper doesn't make you transgender, it's just about the State agreeing with you.
https://www.cntw.nhs.uk/services/northern-region-gender-dysphoria-service-specialist-service-walkergate-park/waiting-list-waiting-times/
https://www.reuters.com/article/us-health-lgbt-transgender-idUSKBN2IM0FQ