Please help me!! A long post but I need some advice😞

So me and my boyfriend have been together 8 months and lived together for 8 months. But known each other for a year. We happened kind of awkwardly because he was getting married but he wasn’t and neither was I.. so when we broke up with our partners I had nowhere to live so he offer me to live with him and it kind of went from there. Well recently I’ve been really depressed and struggling with my emotions so we’ve argued a lot.

Anyways now I’m not one to say I’m not a jealous type because I am. Well this girl he works with he always talks about her etc and wants to go out on days to go for walks and caving etc. Well I asked him if he was interested in her because I was worried and he laughed and thought it was adorable that i was jealous and assured me that I was just being “silly”. He never uses his Instagram much but he likes her photos but never likes mine and says he only like photos of his friends and not any girls. He has supposedly worked all week but I’m really worried that he’s cheating on me with her. Someone please tell me that I’m worrying over nothing because it’s breaking my heart😭