One could argue that getting breast implants is transitioning to some degree. I would submit that anyone having a medical procedure to appear more feminine is transgender. Transitioning doesn’t necessarily mean a transwoman will undergo gender confirmation surgery. There are plenty of women that transition socially or have various procedures done, but stop short of GCS. Getting feminizing treatment doesn’t make you a woman. What’s in your head defines that.
Personally, I would get implants if HRT didn’t produce the results I was looking for. I don’t have any immediate plans to start HRT, but it’s very likely at some point. I want boobs. Presenting as a woman feels natural. In my head I’m trans. That’s all that matters.