Seeking advice going from 2-3 children🫣

Genuinely seeking advice about transitioning from 2-3 children. I got pregnant very unexpectedly after exclusively breastfeeding. My oldest will be 7, baby will be 17 months when new baby is here in 3 months. Most days I’m calm about it but sometimes I feel so overwhelmed. My oldest requires a lot of attention and he’s very hyper active. Im more worried about him than my baby. But I’ve also been pretty physically exhausted this time around due to teaching my daughter to walk. Im constantly bending and picking up. My legs are so sore at night and she’s been fighting sleep again. Our house isn’t the biggest, and it can be noisy. My husband works a physical job, and gone a lot. Im having a hard time picturing a newborn. I don’t really have any friends to support and my marriage isnt the best right now. After having my daughter I fell into depression and I was just starting to feel like myself again when I found out I was pregnant. I hardly ever get time to myself, as is. I guess I’m just ranting.