Please help…

Hi… I am just completely lost. I have a 21 month old boy. He is very low sleep needs and he is extremely energetic and needs CONSTANT attention or he has some of the most severe meltdowns ever. I’m at my wits end… I work practically full time and my husband works more than full time hours. He doesn’t attend day care, he spends time with his grandparents. Which I’m very thankful for. He’s very smart and he’s almost talking. He has 10-15 words and has even begun putting some together. He knows how to undo most of all of our baby proofing stuff so we can’t even step out of the room for more than 30 seconds without the fear of him possibly hurting himself. However when he is with his grandparents he is a total angel and takes such great naps for them (not for my MIL but that’s a totally different conversation but he only goes to her hours specifically once a week if that) and please don’t say “toddlers let out these big emotions with Mom & Dad because they’re comfortable” it makes me so angry to hear that. I took him today with me for my vision exam and within 10 minutes we had to leave because he was melting down so uncomfortably that I couldn’t even comfort him. I am utterly embarrassed because everyone in that office could hear him. I’m so angry. How do people do this? I love him so much but I hate being around him. I feel like the world’s worst mother to even feel this way. People keep telling me that I’m gonna miss this but I can’t wait for it to be over. He’s my first and I will NEVER have any more. He’s cries from the time he gets up to when he goes to bed. I spend all day trying to find thing to occupy him or offering millions of snack and food options but he hardly eats anything! He also throws stuff and smacks stuff out of our hands. He’s so strong too. Someone please just help me. Should I contact his dr? Is this just normal toddler behavior? How do I fix this? I can’t take much more. I want to literally check myself into psych clinic.