What should I be doing?

I'd say continue the story. Your servants will do just fine for now. If anything, go ember gathering. Level your servants.

Keep working on your servants, level 'em and be sure to participate in events, maybe you won't complete the first or two events, but you'll get mats that will help to ascend your servants. Also don't worry about the gacha, keep saving your quartz till the banners you like.
Some events will give you good welfare servants that can help you (Kintoki rider in Onigashima, Scathach assassin in Summer, Kuro in Fate/Kaleid) which all are good four stars servants.
Also keep doing the daily free friend points gacha, there are some really valuable servants in there (Hans Christian Andersen is one of the best supports of the game).

Completing the story is definitely the first priority for everyone cause it give you a lot of Saint Quartzs, which is essentials for pretty much everything, but without the help of the AP 1/2 campaign it would be quite stressful. I suggest trying to find a friend that have some servant that can help you out with your journey, your friends will help you a lot with the combination of servants you can use so try to request friend with everyone you can.
Right now, the sanzang event is really good for gathering materials so please try your best to get as much out of it as you can and use it for ascension and skills, with enough level and skill, any servant can be helpful to their master.(don't need to clear the shop, just try to get all the CEs and some material for future ascension and leveling skill)
Save up on your Saint Quartzs and use it when you have 30 if you really want to find some new servants and CEs, if not, keep it till the event for the servant you like.(i recommend do 2 of these cause some CEs like Imaginary Element and Kaleidoscope can help you turn the battle in your favor if you know what you are doing)
Well, and enjoy the game, this game is meant to be play with out the pressure of catching up to anyone so just play and build the bond with the servants you use in your journey, so relax and wait till those APs back and push through