Hey, I hear you, that must be really scary, especially with the carrying worry. A few things stand out though: the dizziness with breastfeeding is actually quite common in these early weeks, and a lot of mums I know found it got better once they focused on staying properly hydrated and eating enough protein and salt. Since you're pumping 3-hourly as well, your body's losing fluids and energy, so that could definitely be part of it.
What someone in my mum group mentioned was that the combination of sleep deprivation, frequent feeding, and skipping night pumps can really compound the dizziness, your electrolytes and blood sugar dip, and that's when the blurred vision and tingling can kick in. The good news is your gynae's done the main checks and bloods came back normal, which rules out the serious stuff. That said, given you had that BP spike early on and you're still getting these symptoms at 6 weeks with the tingling and shortness of breath, it's probably worth a follow-up with your doctor just to be thorough, maybe ask about your iron levels specifically, since you're breastfeeding and on iron tablets already. In the meantime, really prioritise drinking water throughout the day, eating balanced meals with salt and protein, and if you can, try to rest when your daughter sleeps rather than pushing through.
You're doing brilliantly, by the way, IVF and early labour is a lot on your body.