Yeah, sounds normal to me.
Neither of my older two ever rolled, and dd2 (6 months) shows no sign of doing so either. Dd1 couldn't get into a sitting position by herself until after her 1st birthday. Dd1 crawled sometime around 15 months, walked at 18, while ds started bottom shuffling at around 13 months, but didn't walk till 20 months.
Both are perfectly normal, though they were slow to acquire knock-on skills such as hopping and pedalling a tricycle. Actually, it's a huge advantage to have a late-mobile baby, as you can plonk them down on the floor and go off for a cup of tea while other people's 10-month olds are trashing the joint. By the time they do walk they then have the rudiments of common sense, so you avoid the whole 'walking disaster area' thing that happens with early walkers.
Apparently age of walking has a strong genetic component, so it might be worth finding out at what age you and dh/dp reached these milestones.
Otherwise you just need to develop a thick skin and a line in sarky comments to get rid of old ladies/other mums going "Oh, isn't she walking yet?" I found answers along the lines of, "No, she's too busy solving differential calculus/thinking about European Monetary Union/finding a cure for cancer" worked pretty well.