Oh, I didn't see that other door :o
I managed to get to the portal with only the potion on the second screen. Granted, I did take damage from the spikes that are on the way to the potion, but I assumed I just missed the jump there
(That if we have the same concept of what a "screen" is. I call a "screen" whatever needs an actual transition to reach, big rooms where the camera scrolls with me would be a single screen on my view)