That naturopathic approach is not going to cut it. Your wife needs to be treated by a medical doctor for her depression and her thyroid issues. There is no doubt in my mind that the approach your wife, and you, are taking for her health is grossly insufficient. She is not getting the help she needs. Finding the proper medication for her depression can be and will be life altering. All the symptoms your wife has, my wife had. Right now, this path has your wife being depressed forever and BOTH of you have to deal with the consequences. Like, no sex. Believe me, that situation will continue to make you miserable and more resentful. Been there, done that.
This is definitely a BIG issue. She has health problems which are affecting her mood and she is not dealing with them effectively. I echo those who are saying do WHATEVER it takes to get her in to see a proper physician. These health issues are sapping her energy, her drive and her motivation.
Problem #2. Your wife's dream of the horse. She has the power to make her dreams come true. If she wants a horse, she needs to get a job to pay for the horse. If not, no horse. If she needs a therapy animal, get a dog and love it. She will not take care of the horse. You will have to do that. If she fixes problem #1, then maybe she can get a job and have her dream come true. If she is just lazy, then no horse. Trust me, having a horse will NOT make her less depressed. Her depression is a chemical imbalance in the brain.
She's just idly dreaming about horses and has no intention of doing any work to make them come true. Should you hand her this dream on a silver platter, she'll mess it up because horses require maintenance, ie, hard work! Then she'll moan and groan that she's still not happy. As long as she's looking to outside sources for her happiness instead of addressing her internal issues, she'll never be satisfied.
Problem #3. Your dreams. You need to decide what path you want to take in life. Quit worrying about your wife's "eye rolling". Do you want to be unhappy in your job, your marriage and sex life (lack thereof). If that means changing jobs, then you discuss with wife how to make that happen.
I don't think you can sensibly pursue either your wife's dreams OR yours until you resolve her health issues. When you have an equal partner in your marriage again, instead of yet another child-like dependent, THEN you can discuss your future together and what directions it could go.
I don't approve of her pot usage but have come to accept it. I don't allow her to do it inside the house though. She says medicinal although I'm sure that wasn't the case back in her high school days. I do feel for her though as seems don't ever seem to go her way.
And yet another problem. Pot makes some users extremely apathetic. They'd rather sit around stoned and moaning about how their lives suck than get up and do anything to change things around. Your wife may not even have thyroid issues or depression. It may be entirely the pot.
She's resistant to seeing a proper doctor, so I'm guessing she's probably just as resistant to stopping the pot smoking.
Make it clear to her that the horse dream will not happen unless and until she stops smoking pot and sees a real doctor and follows real medical directions to get better. Put the monetary savings from not buying pot and naturopathic 'meds' towards a horse fund. (Pay for the real meds yourself.) Let her see the horse funds slowly growing while she improves her health and outlook on life.
If she isn't willing to find her energy and drive but just keeps siphoning yours away, you do not have a marriage partnership of equals, and you'd probably be justified by prioritizing your dreams over hers.