How to set better boundaries, am I possibly just being a brat?

My mom has had a rough life. I'm her only child and I'm all she has. We live together but I pay for half the rent and the vast majority of her bills and mine. Id like to live on my own but if I were to do that she wouldn't have a way to support herself so that's not an option right now. I love her to death and she is an amazing mother truly. but she loves me too much & it's smothering me. I don't like to be hugged or touched constantly & she loves to hug and kiss me every chance she gets, when im home. Most of the time I just let it be but if I'm laying down on my laptop focused shell come up an start kissing me on my butt cheeks or she'll blow raspberries on my stomach like I'm a toddler. She asks me a thousand times if I'm comfortable where I'm sitting, if I'm hungry if I need something done and it's really annoying because its so excessive. This makes me uncomfortable and when I tell her this or push her off me she gets mad at me & makes it seem like I hate her. I literally support her & im there for her whenever she needs me & that plus figuring out my own life is already overwhelming enough & the one thing I ask her is to respect my boundaries & she won't do it & instead guilt trips me. I've always been independent & self sufficient and She is a great mother & but wants to be so close & prove herself to be great so much that over the years its only pushed me further away from her. I've tried to talking to her in a respectful mature way but she just guilt trips me & talks about how many people wish they had a mother like her. Maybe thats true, but im telling her what I need from her... its literally all I ask. she ignores me, consequently then I lose my cool and get moody with her. I try to tell her the more space we have the better our relationship can be & she doesn't understand & makes me feel crappy.
How to set better boundaries, am I possibly just being a brat?
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