Firstly I hope your doing OK. As a man we have this thing inside us that wants to protect what we have. For you it’s your daughter. The underlying impression I get from reading between the lines is that you were not ready to have a child. Or didn’t want one with your ex at the least. But what you are doing is stepping up and being responsible for your child. You know you’re ding the right thing and that there’s nothing you won’t do to make her happy and that there shows how much you love her.
Maybe you need some time away from the scheduled visits and some time to focus on yourself to come back refreshed. Maybe a holiday for a week or two somewhere camping anything that you enjoy. If your struggling you need to make sure you look after urself as well as ur daughter. Two weeks away isn’t going to ruin her life. Might ruin ur exes social life for a couple weekends but it’s important to have a balance and not just go through the motions otherwise there will become a point where you could stop caring about spending time with her.