I think you are getting a little confused, it is Gender Dysphoria and Body Dysmorphia.
From what you describe you have/had Gender Incongruence. This is the condition that all trans people have be they trans non-binary or trans binary/transgender. Gender Incongruence is discomfort between your gender and natal sex). Gender Incongruence is a spectrum through a tiny amount through to overwhelming. Whilst sex is normally described as natal sex i.e. dictated by your genitals (even this is not binary because you can have a condition known as intersex where the genital anatomy is confused - medics put an X down for the child’s sexiness this case). Gender is how your brain perceives your sex. For most, of course, these are in line with each other but for trans people they are not.
For neurotypical people the lowest levels will be ignored. The next level up is more of an issue and some psychiatrists believe it may result in hate issues. Beyond this some, as you indicate will be able to live with it with no real issue. Others will use gender neutral or cross gender presentation to cope with it.
Eventually the Gender Incongruence gets destructive and the in is known as Gender Dysphoria. Whilst Gender Incongruence is mainly self diagnosed a diagnosis of Gender Dysphoria is done by a specialist psychiatrist. This condition can lead to depression and is serious. If the patient cannot accept that they are transgender at this stage then the outcome is likely to be bleak but those that do and receive cross sex hormones generally thrive even though society pressures are against them.
Body Dysmorphia is a hate of a piece of your body. Transgender people often have this condition. Around 70% of trans men have it regarding their breasts but estimates shown that with trans women it is about 10% have it regarding their genitalia but around 30 eventually have surgery down there.
Oh by the way, on the age thing I help a lot of trans people that are 60 plus.