Paper thin veins?

So I’ve had a plethora of IV’s and arterial lines in the past two years from multiple ICU and hospital admissions. In this time the doctors progressed from having no issues cannulating me to now never finding a vein and more often than not; using infant needles. When looking for my veins, they are genuinely TINY, absolutely tiny. Perhaps the thickness of 2 pieces of normal paper (some veins if that.)

I drink water very frequently so it isn’t down to dehydration. Is this something that can just happen and go away with time? Is there something I can do to change this?

It’s very scary not being able to be cannulated quickly in emergency situations anymore (I have severe brittle asthma and rarely respond to inhaled bronchodilators in exacerbation and I usually need immediate IV access to adrenaline and steroids).

I went into respiratory failure earlier this year because of the delay of treatment purely because no one could cannulate me anywhere on my body. I’m really dreading if there’s a day they can’t do it in time.