I know a few people that had just a headache or super mild symptoms and only tested when family members and fellow shul friends tested positive
That’s a different scenario that OP. OP had symptoms that merited a test, but not abstaining from
feeding his family attending a Sheva Brachos.
A negative test doesn’t tell you anything so he should’ve stayed home regardless.
As I said in the beginning, I’m not addressing his personal case, just the general Lakewood attitude under similar circumstances.