Try to broaden your life in lots of different ways. Getting a dog was a really good start.
Think of different important aspects of life and create habits that enhance them which also put you in more social situations. So, to keep fit, you could do online yoga or DVD workouts but you'd meet no one. If you sign up for a local yoga class or bootcamp, you are integrating in the community. You may not make friends, but over a year or two if you keep going, you will become good acquaintances with other regulars. I went to fitness classes for two years before anyone invited me for coffee afterwards. But then a group of us went for coffee every week. Then another person discovered we both liked music and started giving me free tickets they got through work. And another started swapping garden cuttings and fruit and home made jam. Suddenly I had some good interactions - not amazing friendships, but more than before. It took time.
Other aspects of life you might want to develop:
Community contribution - signing up to help at a charity or local project like community gardening or visiting in an old people's home. DS made really great friends with other volunteers in a soup kitchen. They go on holiday together every year, and out for bike rides and picnics. They're just lovely people.
Spirituality - if you have faith but don't practice, you could try attending a few local services to see if somewhere feels right. If not, you could join an Alpha course or meditation class just to find out a bit more.
Personal Development - join a class to learn a new skill - languages, creative writing or art, woodwork or cookery.
Travel - if there are countries you want to visit, sign up for group travel - there are specialists for singles including ones with specific age groups. Might not be so easy with a dog, but once he is grown a bit and settled, you might find a dog-sitter.
Bucket list items - just do them, whatever they are, alone or in groups if you don't know anyone who wants to do the same. Could be anything at all that you have ever thought: wish I could do that.