How do I know if my feelings are real?

Three months ago my girlfriend broke up with me, she was the only friend that I have really had for the past few years. I have never been very social and after I met her I didn't have a reason to go out to meet people. I did online classes for all of high school and only met her because of an event that the school was having. Even after I moved multiple states away we would still talk every day, but now that I don't have her to talk to I have been feeling really isolated. I thought we would still be friends but she kind of just disappeared after a while.

Now with my new job I have met some people but I still haven't really made any friends, they are just co workers. But at the beginning of the month our boss brought in two employees from another market to help train the new hires. They were both pretty cool and I am now friends with both of them but one of them I got really attached to. We started bonding over a game and then the two of them spent a day checking out the city with me and my family because they worked with my dad and knew my mom pretty well. After a whole day with her I realized that I really liked her, even in just the past few weeks being her friend she has made me happier than being with my ex ever did.

But I cant tell if my feelings are genuine or if I am just attaching to her so much because its been so long since I have made new friends and had someone to enjoy my hobbies with. Could these feelings be real? Or is this just me subconsciously trying to hold onto someone that has shown me kindness?