Help my son is potty trained but won’t go without me

Looking for advice. My son is (mostly) potty trained and rarely has accidents. However he refuses to hold his own penis and will only go potty if I am holding it. I know it sounds weird but the way his body is made you have to hold it down pretty far otherwise pee will get everywhere so he’s developed this fear of getting pee on him. I don’t know what to do. He has to wear a pull up when he’s at daycare and will sit on the potty but he won’t go. I feel like I’ve tried everything. Standing, stickers, target practice. The last thing I can think of is to just refuse to hold it and go cold turkey. But he gets very upset. He is going to preschool in the fall and has to be potty trained by then so I’m a little nervous about it.