I’m a beginner to piping flowers and I’m wondering if someone can tell me what’s going wrong please?

My Swiss Meringue buttercream is melting as I’m piping. It’s a cool day & I’m putting the icing bags in the fridge when I’m not using them. I’m sure there’s some heat coming from my hands but I have naturally cold hands.

I’m using Sally’s Baking Addiction’s SMBC. It’s worked fine for icing cakes or piping rosettes in the past, and it’s whipping up fine but then just seems to flop as I’m working.

Does anyone know what I’m doing wrong or what’s wrong with my buttercream? Is American Buttercream easier to pipe buttercream flowers with?

I’ve promised to make cupcakes for my friend’s daughter’s first birthday. The theme is wildflowers and I’m a bit worried I won’t be able to make it work.