Dark humour to cope?

First time posting here. I'm 43 y/o and currently 2 weeks post-diagnosis (but I pretty much knew a week before I was officially told). Swollen armpit led to imaging and a lymph node biopsy, and biopsy confirmed breast cancer, total of 7 armpit lymph nodes are suspected to be cancerous. 5 imaging tests later and they still can't find the primary tumour ... but anyway ...

I'm struggling with the feeling of isolation that I think most people experience. But I also keep saying things that I think are really confusing to other people. I have a really dry & dark sense of humour normally, and I'm not sure if I'm struggling to cope and don't realize it? Or if this is a perfectly normal way to cope? I'm seriously starting to wonder if I need therapy.

Example time. Went for yet another imaging session on my boobs today, and if they had found the primary tumour they were going to do a biopsy. They were talking about a research program they have, where they take a couple extra cores and send them off, and they wanted to know if I'd be willing to participate.

My dead-pan response was "well I'm not expecting to have The Girls for much longer anyway, so you might as well take whatever tissue you can get right now". Both of the nurses' mouths dropped open. My mom was there with me and she (thankfully) started cackling which broke the ice. I was told that I was the "most chill" patient they'd ever had. Before my stupid joke, I'd just been very matter-of-fact about my diagnosis and what I knew, like do people normally break down every time they talk about it? What's wrong with me?

Another example. Saw my co-workers for the first time yesterday since I "went public" with my diagnosis. One of them was openly bawling her eyes out, while I'm standing there super confused, not crying myself, and I got so uncomfortable that when she asked when I'll be going off of work for treatment I just blurted out "not sure, but I'll make sure you get a selfie with the chemo machine hanging off my arm!!". It made her cry even harder.

Anyone else I talk to, everything is about pink, and feeling beautiful, and being strong, being a warrior, etc., and I'm just here like "I saved a super twisted dark funny cancer video that I'm going to share on FB with my first chemo selfie!!!" ... and even my closest loved ones don't get it and are regularly shocked.

Is it really that abnormal to be so accepting of what's happening to me?? I cried for a day. I was sad for a few more days after. I don't sleep well anymore and I'm always pretty tired. But I'm going to work and don't feel like I'm mentally struggling. I have down moments, but I'm generally able to just carry on with my day.

Should I be speaking to someone about this???