Can you have a normal level of lymphocytes, but have low levels of t-cells...?

Yes: B-cells may be high-normal. Please keep in mind that both b-cell and t-cell levels fluctuate wildly with life's stresses, infections you may be fighting off without you ever knowing you met them, and who-knows-what else. Unless the numbers are very far outside the reference range (where most-but-not-all asymptomatic people fall) don't give it anotuer thought.