Stress or postpartum??

I went through postpartum with my son. I literally cried once we got home from the hospital... fast forward to now, 2 years later... I just had my daughter 3 months ago, and I've been under a lot of stress, but today I think I hit a bad spot and I'm not sure if it's postpartum or just me having so much stress going on right now.

My husband and I hit a rough spot, and we've both been pretty stressed about it but it hits me harder than it does him. I am currently looking for a job so I can go back to work, but I am just so nervous to leave my children, because Im the one whose been home with them sense they've been born, for my son that's his whole life (2 1/2 year old, and my daughter who is 3 months). We went car shopping today to get a bigger vehicle and I literally cried at the dealership because nothing was going right, and what we wanted wasn't working, and I was just ready to give up. I still want to cry and scream, but I can't because I don't want to in front of my children.

I don't really know if postpartum is hitting me now or not because it was so different with my son. With him, I was actually depressed, I cried once we got home in the hospital because I didn't know what to do, and was very overwhelmed. That went on for about a few weeks and I started feeling better. Now I don't feel depressed, I just am having horrible mood swings and just want some time to myself. ( I hope that doesn't make me a mad mother).

I personally just want to go away for a day to just be myself and get away from my husband and my children. I am a stay at home and I have been sense my son was born in 2014, I don't feel depressed but I feel like I'm going to just explode. I love my children with all my heart and would never want to be away from them but I don't think it's bad of me as a mother to need time to herself for a day? Is it?

I also have horrible mood swings going on, not sure if I should blame that on my IUD (merina) or my body just not being back to normal yet. I am so hard on myself all the time, but I always have been. I guess maybe I could also be feeling like this because I have no friends that ever want to do anything with me. We will text and stuff but that's about it. I can't remember the last time I had me time, and idk if me time will make me feel better or not.

I just want to give up because nothing is going right for me right now...

I do apologize for this really long post. I just need to vent and I feel like I have nobody to talk to... thanks for listening :) and I hope not bashing please.