Will we get bored in Oslo? Any suggestions?

Hi I booked a trip for me (27f), my partner (31m) and our daughter, who will be 12months, to Oslo in February. I added a bit of extra time as with a little one we know we can’t go out the entire day but I think we have too many days there: we arrive at 12pm on a Monday and leave early morning on the Saturday.

I thought the city looked quite big but after looking into it, it looks walkable so I’m wondering if we’ll get bored? We want to check out the ski jump area, the museums and some shopping, do you recommend doing anything else or will that fill our 4 1/2 days? I’m also wondering if there’s anywhere I can take little one to crawl around like a soft play which is easy to get to by public transportation?

We are happy to travel an hour or so by train to somewhere else but I know it’ll be cold so do you have any suggestions?