Hello and welcome to MedHelp's forums. Erectile dysfunction is not as uncommon as people think in young men with 26 % of men under the age of 4o reporting it. We encourage you to speak to your doctor about it. While masturbation can possibly impact this, there are other underlying causes you would need to rule out. So, being able to talk to your doctor is important. With the high number of males who have the issue, they will not be terribly surprised and will hopefully have suggestions for you.
So, how is your mental health doing? Are you anxious, depressed or overwhelmed? This greatly impacts erections and is the reason most younger men have issues. Not all though, so this is why you need to speak to your doctor. And if mental health concerns are at the heart of the ED, addressing those can help too. https://www.webmd.com/erectile-dysfunction/understanding-erectile-dysfunction-basics
Here is some information on reduced sensitivity. That definitely could be impacted by masturbation. I'm linking an older thread here on medhelp where you can see many young men having the same issue and what they say about it. https://www.medhelp.org/posts/Erectile-Dysfunction/Very-poor-Sensitivity-in-the-penis-and-head/show/934579
One thing to note is that nerve issues can also lead to this. This article talks about medial causes of numbing or a less sensitive penis. https://www.medicalnewstoday.com/articles/322694.php Low testosterone can be a culprit as well and often is.
Let us know what you think of this information and if you are able to get to a doctor to discuss this.