My mom is trying to talk me out of having a fourth baby.

I am 31 and have been happily married for 11 years. We have 3 kids so far 5,4 and 6months. We are currently trying to have another. Before anyone thinks I am crazy for trying so soon. We have had fertility issues almost every time we try to get pregnant. So we thought we would just try and that way they would be close in age hopefully even if it does take 1 year to get pregnant. My mom keeps trying to talk me out of having another. Her reasoning is she says what happens if something happens to my husband and I have to try and raise 4 kids all by my self. My husband is relatively health. He does smoke a pack a day and he does drink monsters. I know it is my life but part of me feels like when I do get pregnant is she going to be disappointed in me? Will she love this baby? How do you tell someone your pregnant when you know they won’t necessarily be excited for you? My husband says who cares it’s our life and she will love the baby. I just need thoughts. Also I am a stay at home mom. I homeschool our kids and my mother never watches my kids unless she wants to. My husband also goes above and beyond to support our family. We do not struggle financially. So really I am stuck in my own head with my own thoughts and only my husband to give me advice. And I just feel torn still. HELP!