Going from the apocalypse to X-years post-apocalypse in a logical and realistic way
I'm currently developing a post-apocalypse story idea, where a virus caused the death of a lot of humans and in advanced phases spread to animals and made them insane (don't want to have zombies nor zombie animals, only mutant animals that attacks humans on sight) but the majority of those animals are afraid of lights so the threat is high during the night only.
Now we jump to the story, it's X years since the apocalypse (determining the X is part of the question), in a city that restored a little of the old life. They surrounded the city with walls and guards and started farming and manufacturing for a group of nobles ruling the city (This is not dystopia).
Now to the question. I have the two edges of the timeline, the start of the apocalypse, and the actual time when the story is happening. Only I'm struggling to find what happened during this period and how long it was. I think the only way to answer these two questions is to know what technologies are still preserved and to what level.
So here is the actual state of the technology in my settings (I used a template from an answer I found here)
Medicine
Basic medicine and easy drugs.
Agriculture
Farming & Fishing are there but I'm still undecided if it's with machines or by hand; Animals can still be tamed but at higher risks (if a cow is infected it'll surely attack at night).
Weapons & Self-Defense
Poor people use medieval weapons but nobles and city guards have access to fire guns (either because the nobles hold the knowledge or they lack materials)
Manufacturing
The industry is there (or at least I need it to be) so in my setting, there is a large part of the population of the city working in large scale factories owned by the nobles. 934
It’s basically metal work but I’m unsure what those factories can “realistically” be producing. It can be producing radios for communications or fluorescent light tubes to keep animals away or other electronic parts. I’m also thinking of the walls made of steel and concrete, farming tools and weapons but there is the struggle to make things realistic, you need to know a thing to know the others.
High-Tech
None. At least in the city, maybe in some parts of the country or the world, there is mecha and robots but I don’t think it really matters.
Motorized transport
Same for weapons, there are cars and trucks but only for nobles and necessary work (patrol, food transportation…) and there are bikes for lesser rich people (and horses for the rest). So there are working oil wells and refineries but at a lesser scale which makes the access to cars and fuel very expensive.
Electricity
Hardly maintained but is used for priorities like factories, food storage, defenses, and of course for nobles' houses. Important streets and places are lit by fire during the night.
There is I think the global situation of how I imagine my setting, so how can I go from the apocalypse to this in a logical and realistic way?
(Excuse my English, not my first language) 934