If your turnover exceeded the limits specified in Section 44AB(a) for the financial year 2018-19, you are likely required to deduct TDS under Section 194A for the financial year 2019-20. This applies even if you filed your return under Section 44AD. It's advisable to err on the side of caution and assume TDS deduction is necessary.
11 March 2020
From the plain reading if the proviso to sub-section (1) of Section 194A, reference to only monetary limits specified U/s 44AB (a) 44AB (b) suggests that in your case TDS is required to be deducted. This is safer rather than taking a view that accounts were not required to be audited U/s 44AB(a).