So just to get things right:
there is you 28 and works (do you fully own you own place? If so do you have a mortgage or loan?) You spend a good amount of time round your care giver place and she spends time round yours, (are you only being cared by her or do you enjoy just spending time with her doing anything and everything?) The care giver a 53 year old widow that owns her own house that works (I take it she has no mortgage on said house? Or any loans to pay off?), she gets to care for and enjoys having you when you come round or when she goes round yours. (And Again does she do any more then just care for you?) Lastly there is your parents, how often do they pop in with out telling you? Or if they do tell you how often do they come round par mouth? Are you super close or do you give each other space to do your own things?
If I have got that all right:
the first thing I want to ask you is how much do you love you carer? Are you a full on couple when your are not in little space? (I don't mean to question you relationship with your carer too much it's just very important to know how much you both love each other when talking but 1* full on living together and 2* marriage)
So let's work with a yes and a no to are you a full on couple:
If you are then thinking about moving in and getting married is pretty normal if you are a full on couple (year there is a age gap, what what? Anyone can love anyone they want as long as both people are happy and think about each other), I take it you both think you can live to together perfectly fine since you already spend a good amount of time round theres but it's never truly the same as fully livening in the same home so you have that to think about for one. As for kids if that is something you want and you want to be be your carer too but you dont want to have kids with her down to her age (which is smart since they say both of you should only really have kids from the age of 20 to 45max, if you go past this rule the kids will have problems and that is 100% unfair on them) I think that is down to your carer if she would be happy to share you with a girlfriend that same age as you since this kind of thing would only be unfair on her.
If you are not a full on couple but still get on super well as little/AB and as adults moving in together is not common but not uncommon since liveing on you own is not easy and is always made easier when going all in with another person or people, as for getting married if your not a fully on we live together we die together or religious one or both of you then is it really needed?. I know both side in saying that being married is a visual sigh that you both have accepted each other for all that you are or ever will be for the rest of your lives the other side being that being married is something to be feared financially since you have both tied your self in to something that could go down very badly if for whatever reason you were to break up. (And yes I know its wrong to be fearful of something that has not happened or wont happen at all but being married is one of the biggest financially risks of your life) same thing as before you might go round hers alot but that is not 100% the same as living together. As for kids if you are not a full on couple and you just enjoy being together in your spare time there should not be any problems with you getting a girlfriend your own age, though it might be a bit odd to whoever you end up dating. (If they dont like what you enjoy then they are most likely not for you as they say)
As for if she sells up and moves in with you:
I think I need to know more about where you both are financially (no real number lol I don't need to know that, just if you own your own place out right or not and do both you have a mortgage and or a loan) if you both have mortgages or a loan then it could be a good and a bad thing for her to sell up. Good since you might be able to full pay off any debts you both have and have a bit more money to play with, bad since selling a home is 90% of the time not a good thing (unless you need to upgrade or down grade thanks to life stuff) if you can just rent it out like most other people have said and if you do have a mortgage and or a loan if you both pay off your debts it might be easy for you to get another loan or mortgage because you are young but she will have a harder time thanks to her age.
As for do other Abdl tend to try and move in together and or get married:
I cant say since I am 26 years old and pretty new to accepting who I am/ trying to found out what I am fully. On the other hand if I meet a girlfriend that is a abdl or a carer or even someone that just loves me for who I am do I intend to move in with them? In short yes...... in long I am pretty shy and do things slowly down to a lack of trust in everything so yes but I will need time to learn and trust her to a point where I want to live together. As for would I marry her? Down to my lack of trust and me not feeling like we need a reason not to trust each other I'm not super down for it but if she really wants to and I know we can work it out yes I would 100% marry her for dealing with my shit up to this point haha.
And lastly if you do go all the way (or some of the way) in with her
@Youneeddiapers and you want to be open with it all to not give yourself even more stress just tell your parents how you feel in a way that does not make things confusing, until they hear you out you wont know what they think. At the end of the day your 28 work and live on your own so your parents should (hopefully) just accept that you are doing what you like and trust everyone involved and that at the end of it all you are still there son that they (hopefully) have loved a lot up to this point.
All I can say is good luck and plan everything ahead!
Side note, Lol I have sadly missed 2 full work breaks saying all of this so I hope it helps haha