I can only offer a guess. You really need to talk this over with a therapist who can hear your whole story and who can ask the follow-up questions that need to be asked to come to a real understanding.
So here’s my guess: No news to you, transition is difficult. You started the process when you were only 16. That’s a time when most teens are working out who they are and how to relate to others. You were working on an additional layer of concerns and, perhaps, fears. The need to have compassion for yourself may have overwhelmed your ability to have compassion for others.
Feeling our feelings and knowing what to do with them is part of the process of maturing. In your case, you may have put off some of that developmental task while you came to terms with who you are.
If you aren’t in therapy already, I urge you to find an experienced trans-friendly counselor to provide you with guidance and support as you work on becoming all you can be.
I wish you well.