What you say is not true.  There are many references in the New Testament to gathering to break bread on the first day of the week (Sunday).  This is also the exhortation of the writer of Hebrews below regarding meeting together and the consequences of failing to do so.

Hebrews 10:24-27, 29 NABRE

24 And let us consider how to stir up one another to love and good works, 25 not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the Day drawing near. 26 For if we go on sinning deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, 27 but a fearful expectation of judgment, and a fury of fire that will consume the adversaries ..... 29 How much worse punishment, do you think, will be deserved by the one who has trampled underfoot the Son of God, and has profaned the blood of the covenant by which he was sanctified, and has outraged the Spirit of grace?