Nice to see it can be done, Currently trying it myself with Gateshead managed to get them promoted from BSN to Championship in 4 season pretty much walking the first 3 leagues, struggled alittle in league 1 but won it on the last day of the season.The championship is looking tough though hitting those relegated teams is just a killer, Already hit 3 of them in my first few games and lost all 3 but i see the playoffs as possible with abit of luck because the other teams in league havent put up too much of a challange.
I think staying in the premiership is the biggest problem after getting promoted once you do that you can build a pretty strong team for the second season so winning it in the 3rd season is doable, Hard but still doable.
Dont worry about people thinking you cheat, I got it too and i'd only won the BSN BSP and league 2 at the time which are pretty much the easiest leagues to get out of.Aslong as you know you didnt cheat who cares though.
You did amazing just to stick with the team for that long alot of people can only manage 2-3 seasons and get bored, LLM is clearly the way to go for a long game.