could use some advice

so i’ve been dating my boyfriend for 3 years now, we just had a baby and i guess long story short is i’ve known since i found out i was pregnant that i wanted to marry him. We’ve had some conversations about getting married and he’s explained to me that he’s not ready to take that step and i’ve accepted it and completely understand why, but i get sad and depressed every time i see anything that has to do with engagements or weddings, and i feel like i’m letting it get in the way of my happiness. Are there any tips or coping mechanisms to not let overthinking and depression get in the way of my relationship? i don’t try to take it out on him but he said me being sad about it is making him feel bad and ruins his mood, and i don’t want to be a miserable person just because of my depression. tips?