Yes thats a bad habit, but it would be better if you mentioned exactly where do you hold to delay ejaculation. I am not guessing, so it can be anywhere that you feel comfortable.
Masturbation everyday doesnot kill you, the semen and sperm you release in a day is covered in 24 hours. Unless you had more than once, that still is okay.
Let me talk about a little bit of biology here. Semen comes from prostate and come out through urethral pipe, the same pipe let go of your urine and semen. Urine comes out from bladdar, semen comes from prostate. When you have a hardon, the urethral spincter closes the bladdar line, so that semen can come out. Once you lose your hardon, that directline of bladder gets open again.
Now your problem is, you let the prostate loose and path it takes let go of the semen. This path can let go of your semen but dont accept the sam route back to prostate. This results in the semen stays in urethral spincter, once you lose hardon and didnot let it go out, it gets to only place left, bladdar. Eventually it gos out through the regular way with urine.
That ends the biology class, now what you need to do. If you want to delay your ejaculation there are other things to do, lake take deep breath, stop any movement, dont touch frenulum and there are some more tricks. Be it an early release or delayed, its better to stop the act, try to press PC muscle to stop or let it go. But pressing somewhere is not a good call. specially hard press on the shaft can even damage the vulve that cntains blood during erection.
Somehow I dont think you have caused much damage till now, you may feel a bit pain during pee, that still can be managed by regulating your masturbation and give up this press habit. In case you find pain in testiecle or see the vein there turning blue, consult a doctor. A doctor is the best friend, talk openly with all details, can help you.
Take care and learn the Kegal Exercise, that will help you give up this self invented habit.