Looking for advice on gaining visible muscle with irregular workout routine

Hi all! I was always the weak kid who was bad at sports as kid, which has translated into a dream of having visible muscle definition as an adult - especially in my arms and upper body.

In my life, I've had periods of being very regular at the gym, but the past year has been really tumultuous for my health, and it led to a diagnosis of severe Crohn's disease. I'm trying to go to the gym as much as possible, but some days I just feel like trash and can't.

I'm worried that my dream of looking stronger is unachievable at this point, which has put me in a bit of a slump recently.

Does anyone have any advice? Thank you, really appreciate it! 😊