Hello ! I'll try to give some constructive feedback I'm mostly going to focus on things to improve, but I hope I won't come out as harsh. Feel free to skip comments you find useless or obsolete, I'll do my best to help !
I believe you need to settle for one main font to create some sort of continuity across your strips. It would help show what style you've settled for as well, and unless the difference of font is justified, just keep to a single one imo.
You can find font resources here in order to find what you need : www.dafont.com
2. Art and style
You seem to be going for some quick/sketchy art style, which is nice. However, you might want to make a difference between sketchy styles and messy/careless ones.
Your lineart seems bold and made of a single line (instead of fuzzy strokes, if that makes sense). It doesn't match with going over the edges, stuttering/wavy lines, etc. imo. While you could keep your simple/stylish shapes, you could enhance them by having a neat and careful lineart that doesn't look messy. This way, you can reinforce the stylistic effect of the minimalist shapes without having it look like some rushed stuff you did in 2 minutes.
Some examples of neat lineart x stylish and bold shapes:
You can see here that all styles use shapes differently. However, even if they go for more simple or sketchy shapes, they keep a sense of neat lineart so it doesn't look messy. I think you could improve by doing so as well.
Moreover, that sort of style works very well with the flat colors you've been using.
3. Stories, format, humor
Not going to sugarcoat it: I've come across most of the jokes you illustrate at least a thousand times during my journey on the internet. What's nice with these is that they're relatable to most of us. However, if you weren't one of the first to illustrate them (or one of the most famous to), then you won't draw anyone to your comic: these jokes can already be found in ten other comics who have a larger fanbase and level of fame.
You need to wonder what you can possibly add to these jokes, or let them go all together in order to make something new. If there is no personal touch or originality to be added to them, then you're making a mistake by sticking to them imo.
I can suggest you to try to change these jokes to give them an unexpected twist of your making. If you want to try something brand new, you could use random generators or words/plots/situations/characters to make something new with each episode. There is no rule to creativity because there is no bound to it. If you need more guidance on that, we can talk about it or you could make a thread on this forum asking how to build one-strip comics with humor that sticks out of the regular stuff, etc. Plenty of resources can be used!
4. The "guest comic"
This page makes no sense. It is not related to any of the other pages, the characters are different, and imo it has nothing to do in the course of your series because it simply disturbs the reader. If you want to share additional production, you could make another series, or post them on another platform, etc. Keep this series' webpage for The Otter Side, so that it looks clear to the reader
That's all I have for now! It feels like you're pretty young (in age or as a creator) and are still looking for your "thing" in the comic world (please tell me if I'm wrong!). No shame in experimenting and getting inspired by popular trends, but imo creativity truly surfaces when you break free from these chains of "popular stuff".
Good luck and happy arting!