Should we be one and done?

Ive always pictured and wanted two kids but since we’ve had our 18m/o my husband and I snap at each other a lot more - normally due to tiredness and this comes and goes in phases it’s not all the time - but I get really emotional when this happens and feel like our marriage is falling apart (he’s very relaxed so isn’t really worried when we snap and knows it’s just from stress) but we never used to snap and I hate any kind of confrontion so just get so upset by it Which brings me to my question. I’ve always wanted two kids and can’t imagine not experiencing being pregnant etc again but I’m scared for my marriage, I’m scared it won’t survive if we have a second child. And how do I tell him that when he doesn’t think there is a problem or at least he says it’s not 🥺 I love him so much and would love to give our baba a sibling but whenever we have these moments it makes me think we should just be one and done and not had more stress 🥺 Any advise,help experience with this is appreciated ☺️