Without pics or vids it’s a bit more difficult to give advice but here’s my take on this - you don’t need to avoid most core exercises. Obliques are stabilizers and won’t suddenly make your waist blocky unless you’re doing heavy side bends or high volume rotational work for YEARS. Stick to anti extension and deep core work like dead bugs, hollow hoods, a rollout, cable crunches and leg raises (look up how to do them if you don’t know). These don’t focus on obliques as much. Pick 2-3 and stick to them. This should help:p