You are correct that if the Bitcoin network is processing transactions within a reasonable timeframe despite high traffic, then there is no overload on the network. It seems like you were able to successfully send and receive transactions during these periods of increased demand, which means that your experience was not affected by any form of interruption or bottleneck caused by an overload.

However, we have seen instances in the past where high transaction volume coupled with a lack of mining power led to backlog and congestions on Bitcoin's blockchain leading to delays and higher than normal fees. Moreover, it's entirely possible that certain users may have had different experiences from yours during those periods. If too many transactions are happening slower due to an increase in demand beyond what miners can confirm this could potentially be classified as an overload.