The Finn joined Alfa Romeo from Mercedes ahead of the 2022 campaign.
Despite a strong start to the year with seven points finishes from the opening nine weekends, his season dipped from the British Grand Prix onward, with just two further scores.
Asked to assess his year, Bottas said: "[It was] up and down.
"We started really strong, then we suffered with quite a few reliability issues and some bad luck as well.
"And some teams were able to maybe out-develop us a bit, in a way. But I think we were able to regain some momentum."
Alfa Romeo finished second-last in the constructors' standings with just 13 points in 2021.
But by the fourth race of the year, Bottas had exceeded this total on his own but he warned this is a "long-term project".
"We're focusing for the years ahead, and for the years ahead of us we see we can make good progress," he added.
"So overall positive if we look at where the team comes from in the last few years."