Is husband cheating?

So my husband works with a few women and one of these women he’s known for awhile. We’ll call her Jill. Well Jill likes to text and Snapchat my husband all the time and my husband has been kind of hiding his phone from me when I’m near him. So I decided to try and look through his phone, well to my surprise he’s changed his password. Jill is known for flirting with other men at work as well. But my husband has told me in the past that she’s a badass and she’s nice, shit like that. Well he decided to tell me that she bought him a really expensive baby carrier. I said it’s weird and suspicious and he got all defensive and said she’s just trying to be nice. Fast forward to this week, I was at his work with him and he walked down the hall ahead of me and Jill was standing around the corner, she saw my husband and got extremely excited to see him. He said hi and quickly turned around and looked at me with a nervous face. Then she proceeded to walk past me with her head turned away from me looking at the ground. Idk what to do, I’m almost half way through my pregnancy and this is stressing me out so much.