Part of you problem is probably the filter size. A small sand filter has quite a bit of head loss so no matter what size pump you have, the flow rate will be reduced by small plumbing and a small filter. Also, forcing high flow rates through a small filter, which you are probably doing now, will most likely shorten the life of the filter. You can't do much about the plumbing but it might be a good idea to increase the size of your filter a couple of sizes.

But even with that I am still surprised that the flow rate would not be high enough for all those features. A few questions:

Can you be more specific as to what happens when you try to run all three features?

What is your clean filter pressure and gauge height relative to the water level?

Are there three separate return pipes going to the three sets of features?

What is the distance between the pool and pump?

What is the current make/model pump you have?