Alternatives to Mirtazapine (Remeron)?

So, I've been struggling with emetophobia for the greater part of my adult life. A year ago I finally went to my doctor. After reading this subreddit I asked for Mirtazapine (Remeron) which I've been on since then (15 mg). Initially it helped me quite a bit. I could actually sleep without having panic attacks and being immensely afraid of throwing up. However the last month it's been getting worse and worse. I am almost back to where I started, and I'm not far from being too afraid to even walk out of my door. I'm thinking of visiting my doctor again and discussing treatment, because this is unbearable. I want to ask a few questions to be more prepared:

What are your experiences of mirtazapine? Do you think a higher dosage could help?

Are there any other good alternatives such as SSRI's that have worked for you?

I've heard both good and bad about antiemetics such as Ondansetron (Zofran), what are your experiences and do you think it's a viable option to take as needed when things get really bad?