Since you are fairly new here I'll make some assumptions about your knowledge and experience, so here goes, no offense intended.
The shape of your hull creates a "center of lateral resistance" while the sail plan creates a "center of effort". When these two centers are aligned per the designers intents then you would have some weather helm, just enough to be safe from broaching.
When you sail with only the main, the center of effort moves aft and produces more weather helm. When you sail with only the jib
, the center of effort moves forward, reducing weather helm and maybe inducing lee helm.
Likewise a main with too much draft (full bodied) will move the center of effort aft creating more weather helm. This is called a "powered up main". Your boat needs both main and jib
to be balanced when going to windward, and in the wind ranges you quoted that would be the best set-up. As the wind increases (over 15 kts.), you probably need to reduce the main first by reefing, and then reduce the jib
by moving to a working jib
or rolling up the jib on the roller furler
if you have one. And keep this up until you have minimum sail set. Hopefully you will be in a safe harbor at this point and not need to employ storm weather tactics.
Too much draft in the main can be a problem with an old, "blown-out" sail (one with a big belly), but if your sail is in good condition, then flattening the main can de-power it and relieve weather helm. You do this using the "clew outhaul" and the "cunningham" and the "traveller and main sheet". Also, luffing can de-power it for gusts.
Without a center board you cannot change the "center of lateral resistance" except by healing, so all helm balancing must be done with the setting of the sails or changing the point of sail, lest you make too much leeway. Given you need to go where you are pointed, then your options lie with the set of the sails, and that is where the fun is in learning to maximize the performance of your boat. Too much heel adds to weather helm and loss of rudder effectiveness, so reducing sail lets you "sail on your feet" resulting in better speed, more control and more comfort. Especially for your white knuckled crew.
Some boats can point pretty well with main alone, some with jib alone, but all boats point better with main and jib balanced for the conditions.
Hope this helps.