Am I just being overly suspicious in my relationship?

I have a new serious relationship, a little over 1 month long.

He is still in contact with his ex, in fact rather has a friendship with her. Usually that is acceptable only if they have kids from their relationship (they don't).

I asked him about it because he could tell something troubles me. He started talking about his past GFs and that this one is the only one he still talks to because they have been friends prior to getting together and that when they got together it was never really working out (no chemistry despite both of them being attractive). He said I have nothing to worry about, that there were times when both of them (after their break up) were single at the same time and still didn't get back together because they don't match.

I dared to believe him, but I cannot help this feeling of being so uncertain and little jealous probably too which I know is natural. I don't wanna jeopardize this relationship by my own faults and insecurities, but the fact that they still are in contact (rarely in person, texting quite often though), they keep liking/hearting their photos and he still got old photos with her on FB (he said he forgot about them because he don't post often), is just EUGH...

After our talk he said he's glad it's nothing important that troubles me (he was worried I might not like him anymore), that there's nothing but friendship between them, but yesterday I told him that I felt like the matter wasn't really solved and he was surprised, he thought it was (I'm glad I talked to him about it, but later I realized I feel more suspicious than ever).

• He feels like it's wrong if he has to change anything about himself or his life for the sake of a relationship (I kind of understand what he means but still).
• I told him I just feel like she might be more important to him than I ever could be - he said it's not true, but wouldn't he try to compromise at least?

Am I overreacting?

Am I just being overly suspicious in my relationship?
Post Opinion