In answer to your questions (in my opinion)
1, if you had "breast buds" you'd know. They are firm lumps directly under the nipple, they range in size from a small "pebble" to much larger. They would be very tender, pressing on them hurts. If you have lumps in your breasts, it always best to get them checked.
2, A mammogram won't confirm anything as, there is no such thing as male or female breasts. There is simply breast tissue. There is very little difference, men can nurse babies. This is a recorded fact. The only reason women are incouraged to have mammograms and not men is, the tissues in human breasts are sensitive to estrogenic cancers, men have a lot less estrogen therefore, a much lower incidence of breast tissue cancers.
3, there are a lot of different conditions classified as "intersex" or Disorders of sexual development. Many are chromosomal and can be detected by a karotype test however many are known as mosaic chromosomal disorders and are harder to detect. Many of these disorders are coupled with intellectual disabilities, infertility (often how they're discovered)
Disorders that are physically visible are usually operated on at birth, such as incomplete penile growth (particularly affecting the position of the urethral opening in "males" and fused/partially fused labia in "females" Undesende/bi-differentiated gonads (one ovary, one teste) However, your parents would have been informed of this when you were born, so you'd already have your answer.
4, a cat scan won't show anything like that I don't think...
5, by all means get your bits checked, it never hurts to have a checkup
6, I can't help there as we have socialized health care in my country, meaning health serivces are free, no insurance required.
Finally, I have no idea why you'd consider being intersexed as "lucky" A lot of those conditions aren't much fun for the people who have them.
Basically, don't look to simple physical biology to feel justified in who you are. It's unhealthy... And a bit offensive.