Well, consider this, not only are you adjusting to life with a new baby, but your body is now adjusting to life without a pregnancy. I don't know how long it takes for the body's hormones to return to pre-pregnancy levels after delivering a baby, but that might be a factor in why you're suddenly feeling so anxious. The fact that the body also produces a new set of hormones after birth to stimulate the mother to be, well, motherly is also another factor.

If you're breastfeeding your daughter, and thus, are unable to take certain medications while doing so (medications that are unsafe for babies), you might have higher levels of anxiety than you'd otherwise normally have if you were able to take them.

Then again, I don't know what course of treatment you are taking for your MI, so I wouldn't know what medications you are or aren't taking, baby notwithstanding.

I often think about what it would be like to question the gender I was assigned at birth, and if I would be more comfortable with myself if it were changed. However, these thoughts are only fleeting at best, and I really don't struggle that much with them. I guess you might be going through something a bit more severe, but around the same lines of what I am. If you're seriously concerned about your emotions, anxiety and these thoughts of questioning your gender, why not seek out a therapist to discuss this with. They are there if you need one.