How do I ADC?

Ok so I haven't exactly played too many ADC games recently but for the ones I have played I've been having quite a lot of trouble having "enough" of an impact on a game. Most of the "contribution" I have to my team is protecting lanes from super minions alone while the rest of my team is out fighting (which I'm okay with, I'm not exactly in risk of dying and I'm also getting some nice gold) but obviously that's not gonna win you anything.

Issues I know I have that more or less comes with experience is probably CSing which I am absolutely horrendous at, especially in the early levels during laning phase so I'm constantly working on that.

My main issues are:

• What do I do against assassins? For instance, I feel like if I'm in range to deal "sufficient" damage (not just poking with abilities) I'm in range to get blown up and of course, subsequently, where I'm safe, I'm not in range to deal "sufficient damage" to actually contribute in damage.

• What do I do if my team has no sufficient frontlining capabilities? e.g. Overall squishier team comp. I've come across this time and time again where we lose a lot of upfront teamfights since our front line is weaker or non-existent and thus I don't really get much protection or room to breathe as a backliner. I'm not blaming lost fights on our frontliners not playing well, just that our frontliner champions are naturally weaker than theirs. A good example would be someone like Garen verses the enemy Malphite. Garen could pose a threat to perhaps just one person, but he's easily kited and ultimately, in order to "pose" a threat to the enemy threat, needs to rush/charge in alone deeper than everyone else, thus leaving the team. Of course on the other hand Malphite, if he lands one good R, their team wins the fight instantly. So, not players being better than one another, but champions who do a better job at teamfighting.

• What do I do if my team is behind but keep forcing fights when I'm either not there or can't be there? e.g. I've had a game earlier today where my Fizz, despite being incredibly underfarmed kept wanting fights and perhaps due to his toxic nature, the rest of the team would rather fight to make him feel better instead of (on multiple occasions) protecting side lanes that are getting shoved in by massive minion waves. Every time they wanted a fight I was essentially stuck between choosing to fight with them and perhaps risk losing everything or going to protect side lanes from being shoved in but risk Fizz getting tilted out of his mind. On multiple occasions that game, I chose the latter, since as an ADC, if I have as much farm as possible, I "could" become the win condition, though of course at the expense of Fizz's feelings (which unfortunately I couldn't really empathize with). Ultimately they lose far more fights than they win and they blame me for not being there (which technically isn't wrong). Ultimately, what exactly do I do in cases like this?

• Now this one's quite specific but it's a situation I run into basically every game (because I'm terrible). Let's say my turret goes down and my lane gets pushed to my inner turret. All is fine since I get more "room/safety" to CS said minion wave, however once I finish CSing said minion wave, I'm basically back to the "river line" which, without an outer turret, makes me super susceptible to being flanked, ganked and banked. I can't really ward up key entry points either since I could only really have 2 of my own wards maximum (trinket + Ctrl Ward [up to 3 with Klepto but I don't play Klepto ADCs like Ezreal]) and even if I do, everyone has a dash these days so they can just bypass the warded routes entirely to flank that way. Is there really a "remedy" to this? Or am I supposed to only last hit to make the wave push back as slow as possible for maximum safety time?

Basically a filthy unranked casual who still somewhat wants to be competent at ADCing in normals and have some form of contribution to the game.