Simply the act of detransitioning doesn't necessarily make a person "not trans". You still wanted to transition and weren't comfortable living as female, so it didn't make your gender female. And you also can't change your gender by simply detransing. Just like if a cis person would transition wouldn't make them transgender. I think it comes down to that ultimately, transitioning (and by extent detransitioning) is a choice and an action but being trans is something you simply are. So no matter which path(s) you take, if you are trans then you're simply trans and there's no degree on how trans you are.
Some people detransition and don't go back into transition, but are still trans cause they still have that same disconnect to their bio sex and/or don't genuinely identify as their sex. They just choose to live as their bio sex for various reasons. Safety, family being unaccepting, financial and medical reasons are common for that.
Not everyone who detransitions realises they were actually cis all along. But for those who do, and come out saying "hey I'm cis" they're of course not trans then, by their own words, even though they've transitioned. But I don't think that applies to you at all. I'm one of those few transitioned cis people, so there's a big difference between your detransition and my detransition, to give you some perspective. Cause I'm regretting my transition and happily identify as female. I love being called a woman and embrace being one, however I still hate my birth name so I picked a new female name instead (cause cis people can hate their birth names too). I'm afab and went the ftm route, also medically, and I used to identify as male. But I would never want to transition again. It makes me shudder at just the thought of doing so. I'm a girl! I'm even excitedly looking forward to reversing some of my transition so I can feel more womanly and connect better to my body. I don't think most trans guys would feel that way.
The way I see myself is that I'm cis because I identify as the gender that corresponds with my birth sex, but I still have a lot of things in common with trans people because I've transitioned and I can't quite relate to other cis people anymore. My journey is very different from the vast majority of them, I'm not cis-passing anymore, to many of them I "look trans" and I get flack for that sometimes. I detrans because I don't identify as male anymore, because I missed being a woman, and cause I figured out that I was wrong about having dysphoria. That summed up, I detrans because I realised I'm not trans. But me detransing is not what's making me cis. Theoretically I could have kept living as a trans guy while knowing within myself that I don't identify that way anymore. I would in that scenario be a woman living/presenting as a man. But I wanted to live/present as a woman instead, and I felt wrong as a guy, like I was living a lie. So I made the choice to detrans despite knowing how hard it would be to go back, both socially and medically. For me, detransition is an act of self-actualisation and being true to myself.
I'm sharing that about myself just to highlight that detransing doesn't determine one's gender, only really one's gender presentation, but barely even that, cause I know of a lot of detrans women who still present male... That's getting into more complicated stuff like the difference between detransition and re-identification and how those overlap a lot. Basically a "detransition" is merely the action of presenting as one's birth sex again after a transition, and/or undoing/stopping a medical transition. Like for example a trans guy could detrans while still feeling like he's truly a guy. While "re-identification" is when you don't feel like you are the other gender anymore. Like a trans man no longer feeling like they're a man and instead feel like they are and want to be a woman, as in my case. So I fit both those terms but I don't think you fit the latter? I think those terms blend together a lot and they're all in the same kind of field, but I also think there's an important distinction to made about them. Okay this got a bit ranty but... yeah.
As for your other question. I have heard from a few trans people who have temporarily detransitioned to then later transition again when they felt safer/more ready to do so. There are a few on youtube who've talked about having done so. Isla Rose is a trans woman on youtube who's talked about having done that. I think she titler that vid of her's "I regret detransitioning" or something like that, and it's a few years old.
