When is it okay to have a baby shower?

Hey gals. So this is my 4th baby, but my first girl. I had a baby shower for my first son over 3 years ago and haven't had a shower since. Is there some kind of etiquette or "rule" on only having one shower or is it appropriate to have one years later when it's your first of the other gender?

It's just that my family is really "old fashioned" like that and so they don't even do little 'Sprinkles' for 2nd 3rd and so forth babies. which I'm always really bummed about because I would have loved even a simple little celebration for each child. Nothing big and elaborate like the first shower, but you know what I mean? But especially now that I'm finally having a baby girl, I have sooo much I need to get and all the big things like a swing and stroller and car seat are old and worn out from my other kids. So it's almost like I am really starting over. But it's not like I can just ask for a baby shower because then I just feel like it's an obligation and not a fun celebration anymore.. ya know?