Other people being dismissive is sadly par for the course. I was particularly riled recently when a friend (to whom I am 'out') described the ongoing problems their son's girlfriend is having, whom they know well. To me it sounded strongly like ASD should at least enter into consideration, so I asked if they were in a position to bring this up to their son's girlfriend in a constructive and positive way. They said perhaps.
It seems I was taken seriously enough for them to read up on ASD a little, but still, my friend told me a few days later that they didn't think ASD had anything to do with it, based on what they had read. I was dumbfounded. Granted, I don't know the young woman in question, but if what I was told about her (in some detail, too) was accurate - and I'm obviously intimately acquainted with what HFA/AS can be, and this friend knows that - then I don't know how the possibility could be dismissed so completely on the basis on an unnamed source on the internet. The opinion of the living, breathing person they know who lives with HFA/AS has less weight than their second-hand opinion based on (likely also second-hand) information on the internet! And their research likely didn't consume hours, let alone continued reading over months and years, coupled with first-hand experience, like it did in my case. So, yeah, I was pretty miffed at the categorical dismissal of ASD as a possibility for what the young woman in question might be dealing with. I also thought it was a shame for her not give her the option of deciding for herself, in case she's not familar with ASD.
I suspect it's kind of like the OP mentioned - it seems people want to tick the boxes to all possible associated (derivative) symptoms before they take ASD seriously (or have that official 'letter of approval'), ignoring that almost no one has every possible problem and comorbidity associated with ASD. As a random example, I have a mild degree of prosopagnosia, others on the spectrum don't. But I can read other people's emotions/body language quite well while some others can't. On that basis alone I've been told by random people - not medical, psychological or mental health professionals even - that no, I am not autistic. And they were dead certain! Although I have two qualified diagnoses, decades apart, one of them fairly recent. The ignorance out there is really quite breathtaking.
Keeping your own council, as was suggested upthread, is a good idea. Personally, I think that people want to diagnose autism the way they diagnose the common cold. If you have a cold, you have the sniffles. If you are autistic, you must be Rainman. Obviously that's nonsense. Even within the so-called triad of impairments, there's lots of room for variation within and between the categories: you may cope well with friendships (perhaps you have learned over time whom to befriend and whom not to), but not with work (less choice re who, how, what) (social/social). You may not use language as a social tool, but understand sarcasm (language & communication/language & communication). You may need routine, but may be able to display empathy closely enough for NT society to understand (social/imagination). (I say display empathy because that's really what should be said when people refer to the supposed 'lack of empathy' among autistics. Otherwise, we'd be sociopaths. It's unfortunate that, in the case of empathy, the word is used for the presentation and not the emotional capacity. We don't lack empathy in the least just because we're not all cuddly. Plus, the display is all too easy to fake, especially for many NTs, who are relatively untaxed by the social side of it.)
With everything I've read and experienced over the course of my life so far, I put a lot of stock in the Intense World Theory. It has the added upside of bypassing the deficit model, which I personally don't subscribe to, but the triad of impairments inherently does.
But just for argument's sake, let's say no one ever diagnoses you as autistic. Do you, as the only person who lives your life, find the model of autism relevant to you? Then it's relevant to you and you should use it! In the end, if it is not assistance from a government/official body that you are seeking, the only thing that matters is the information that you, and only you, find relevant to your life and your experience, regardless of categories, labels and diagnoses. I don't think categories, labels and diagnoses are useless or detrimental in this case, but they're not the be-all and end-all, and if getting the official stamp of approval for them should turn into a problem, it doesn't invalidate your aggregate life experience and should not keep you from using less formal help (as opposed to the help from government/official bodies only available on diagnosis) that is available to the group with which you identify, nor should it keep you from using the name of the condition.