Dizziness and weird symptoms for the past 10 months 😭

I am 22 years old and I want to cry every single day. I am just so sad. I can’t work, I can’t do anything, and I feel like I am never, ever okay. I got COVID back in April 2025, had my son in May, and then this absolute nightmare hit me full force in August. It has been almost a year of this and I feel like this is my forever.
When I walk around, my head feels so dizzy and bobbly, like I am constantly walking on a trampoline. My brain feels foggy, my eyes feel slow and tired, and my chest feels heavy and tight when standing. Going into stores like Walmart completely overloads me and triggers terrifying adrenaline rushes, panic attacks, and severe near-fainting spells. Hot showers make me feel like passing out, and even sitting down I get awful head rushes. Even just going outside briefly and coming back into my dark house makes my vision go so blurry and dark, which terrifies me. On top of that, my gut is a mess. I get severe nausea, stomach burning, diarrhea, and intense heartburn that leaves me feeling completely sick and empty. I also get severe numbness and tingling in my fingers and arms sometimes.
Midodrine didn’t work for me at all, and I’m no longer taking propranolol. I just started Tirzepatide 1.1 recently and the nausea and dizziness are so hard. I vape nicotine too. The only time I ever felt a bit of relief was when a physical therapist worked on my neck, but the dizziness always comes back.
I've had a clean CT scan and a clean brain MRI, and my VNG ear test was completely normal too. My sitting blood pressure is 104/70, but it drops to 98/68 when I stand up. My EKG showed a sinus rhythm of 82 with several nonspecific ST changes in V4-V2 and aVL. My echocardiogram was completely normal with an ejection fraction of 55 to 60 percent, and my 14-day Zio patch just showed normal sinus rhythm and sinus tachycardia ranging from 41 to 179 beats per minute, with rare PVCs.
My labs from April show my Vitamin D is dangerously low at 8, my ferritin is low at 30, my hemoglobin is 14.3, my TSH is 0.34, and my B12 is 403. My doctor officially assessed me with Postural Tachycardia Syndrome and Orthostatic Intolerance triggered by COVID and childbirth, along with the severe vitamin D deficiency and low iron.
I am so desperate for answers. Has anyone else felt like this postpartum and actually gotten their life back? How do I fix this when the first-line meds fail?