Three year old constant whinging and tantrums, possible ASD

Hello IMs, I need to vent and just to know I'm not alone. My three year old has a speech delay and is going to be assessed for asd during the year. His behaviour is so utterly draining. I understand it, I know he's not deliberately being naughty, and I know that he's only acting out because he gets overwhelmed and frustrated and doesn't know how to handle it... But it is so, so draining. It feels like everything is a battle. He hates getting dressed, wearing shoes, sitting at the table, getting it and out of the car. He over reacts to the smallest things, like his food touching on his plate, his milk not being filled right up to the top, we gave him a banana that was cut in half instead of whole... Now he has even started throwing tantrums when we get dressed, wear shoes, go to the toilet, eat something, he screams and screams for us to stop and gets himself all worked up just because I'm wearing a jumper! He is so clingy and sooky all day, he just constantly whinges and can't tell us what he wants, so we make suggestions and then he screams no no no no! He gets stuck on repeat and will scream the same thing over and over again, not cookie not cookie, don't want cookie, not cookie not cookie, just constant. The only time he is calm is when he is snuggled up with me on the couch watching tv and I feel so guilty that he watches so much tv, but the whinging and tantrums wear me down. I can't think while he's screaming and tugging at m. I feel like my friends and family all think I'm just not setting boundaries and judging me for being too soft, that it's just normal three year old behaviour and I need to ignore it. And maybe I am, I'm just so exhausted and it really does feel like these are above and beyond 'normal' tantrums. I do try to set boundaries (if he is screaming at me to take my jumper off, for example, I refuse, obviously) but he finds the basic stuff of life (dressing, feeding, changing, transporting) are all so distressing and challenging already that I haven't the heart or energy to add more burdens and expectations. Ok, I'll stop now, as I said, just needed to vent.