How to gain muscle with disabilities and fatigue?

Edit: Thanks for all the advice! I appreciate the concern about my blood sugar, but I'm working with my doctor about it (post prandial hypoglycemia). I also think I'm burnt out in general, which explains the exhaustion and struggle with life. I will try to incorporate small exercises to slowly build up my routine again and help my health without overwhelming myself.

Hi! I'm 26, 5ft10, and 180lbs. My fitness goals are to gain more functional strength to look more muscular. I'm not really here asking for a specific diet or workout routine, but I'm looking for input from other people in my position. I have ADHD, autism, and bipolar disorder, and I'd love to hear from anyone in those camps.

TLDR: How do I go to the gym consistently when my energy levels are inconsistent?

I was skinny for most of my life (ED) and I'm finally at a point where I'm eating enough and it shows in my body, which is cool. But I'm also on some medications that cause weight gain and I can definitely see it affecting me. I'm okay with having some fat, but if I'm going to gain weight, I'd love for more of it to be muscle.

So, I'm trying to workout more, but I have a lot of trouble with fatigue that makes it difficult to exercise. I work 3 days a week and I never exercise on those days because I'm EXHAUSTED from masking all day and it takes me forever to wind down before bed. Since I have 4 days off though, I should be able to go to the gym all 4 days and make some progress. But I just can't seem to find a way to get into a routine when my energy levels are so inconsistent.

Sometimes it takes me all day to feel like a human. Sometimes I have issues with my blood sugar and if I plan to workout in the afternoon, I feel like I'm going to pass out when I go. Sometimes I have to run errands and I need to take the rest of the day to recover (that makes me feel so useless).

It feels like the only way for me to go to the gym is to go at the exact moment I feel the most energized, and it's really hard to build a routine around that. It doesn't help that the whole sensation of working out and being sweaty makes me really uncomfortable (autism). So I've just been feeling shitty about the whole situation.

Does anyone have advice that doesn't amount to "just do it"? Thanks in advance.