Thanks for your important letter. The love between the two of you seems very warm and genuine, and the inhibitors your speak of, an antidepressant and your natural biorhythm, makes sense.
But I think a few sessions with a qualified sex therapist would be very helpful. Here’s a link to an organization that has information and referrals for you. They can help you find ways to approach each other and support each other as you try to conceive.
The key is to keep a warm and loving sense of play and exploration. Both of you have had relationships with the sexual response has been problematic. You’ll need to approach your relationship with each other differently. A qualified sex therapist can help you with this.