Is there any way to get prescribed stronger migraine meds?

No it isn't, you are an obvious abuser of these drugs, you are trying to access more powerful ones and your professional medical opinion is that you can just pushing through the effects with higher doses.
Your complete disregard for these risks will logically result in a lethal dose - it would be literally insane to think self medicating more and more opiates wouldn't end that way.

I'll only get stronger ones if I can get a doctor to prescribe them and so far my efforts have been futile

Your intent is the part that matters, not that you've failed so far.

I'm going to have a spontaneous OD from all that intent?

You're going to have an OD from the increasing and uncontrolled amounts of opiates you consume - some things are easy to explain, opiate addicts overdose, you are an opiate addict.

Implying I'm going to have a fatal overdose on OTC headache tablets is a bit of an overreaction

Paracetamol is an OTC tablet and it's perfectly possible to die from a paracetamol OD. Co-codamol contains paracetamol and you want more codeine so it's not outwith the realms of possibility that you might get there one day.

cold water extraction

and you want people to believe you are not an addict or a troll?

Addicts use to get high, I'm taking OTC painkillers to manage my pain, I could be physically dependent but not addicted seeing as I'm not getting high

Not what I'm currently doing, just a possibility for if I have to increase my dose in the future

Addicts use because they are addicted and can't break a cycle or take responsibility, like you.
If you just intend to keep upping the doses of the drugs until you OD I fail to see why getting high matters, you'll still be OD'd - If there is a situation where you just keep upping these opiate doses in secret and not ODing, I'd love to hear it?
Do you realise most pain killer addicts didn't get into it for the high? I know you'll deny or deflect, but it's the facts.

That's not the point. The fact you are even considering it is.

I'll find a stable dose that works for me and then increasing it

There isn't one, you're too far into the abuse already.

Been successfully self medicating for way over a year now

Yeah it all sounds like it's going great, I'm jealous 😬

Well I've not come anywhere near an OD so yeah its all going just fine

How are you measuring this? graph paper or one of these?

How are you measuring this? graph paper or one of these?