I've noticed that recently-the part month or so-I've not been able to stay in the practice room or in rehearsal as intense since my chops don't hold up. I know part of this is because I have braces and the lip protectors I use makes my lips pucker out even more. But I've been using these for so long of time now that i'm very confortable with them, but now as I said my endurence is decreasing.

I've tried to come to some sort of conclusion
#1-I play 1st part on everything and more everything I play is a medium range above the staff, nothing too high...such as Dance Prelude, Overture Jublioso...those type of songs.

#2-I just had to fix a problem over a few months where my mouthpiece was sliding off too the side of my lips-thats fixed now

But I don't know how to go about this, everytime I plactice for a long amount of time (which I do 5/6 out of 7 days out of the week. that depends on how late I get home from working and how tired I am). I don't want to hurt myself or anything on this, I'd figure that wouldn't be a smart thing to do since I have many performances comming up.

But can anyone help? Sorry this is so long.

a few things...
Lack of endurance can be caused by many factors, so without hearing or seeing you play, it's impossible to diagnose online.
However, some common things that affect endurance issues:
too much mouthpiece pressure
change of mouthpiece size
change of embouchure (which you said you did)
doing too much work with the chops and not enough with air support
playing too much music that is beyond your range capabilities (or pushes the envelope)
having to lip notes into tune/not centering notes
there are many others.
My question to you is, why did you feel the need to change your mouthpiece placement? Many players play with the mouthpiece off center, myself included. The trumpet player in the brass quintet I play with plays way off center, and he's an amazing player.
If you tried to change mouthpiece placement, I'm not surprised your endurance took a dive. You're using a whole different set of muscles.
but like I said, without hearing (or better yet seeing) you play, we really can't help you much. Do you take private lessons?

I do take private Lessons from Morehead State university's in kentucky trombone's professor. She told me to change it since I've never played off to the side before. She told me that it could effect my playing when I start playing up where she does and start to really take my soloing to the next level.

But from your list, It may be too much mouthpiece pressure, the lipping of the notes into tune since thats the biggest thing I've been working on . But I havn't asked her yet, and next time I see her I'll ask. but the music its deffently nothing beyond my limits. I would have easly be able to play the basics of all the music I have last school year, not musically, but the basics.

Air support, thats another problem, but she helping me with that. I used to hunch over and block my air...but thats fixed now...

I'll ask her, Thanks for the list of things, which all of which I need to work on, just more of the things more than others.

Well, since you do have the benefit of a good teacher who can actually see and hear you play, I would recommend you focus on her teachings. She has a perspective we cannot have.
Normally I wouldn't agree with the mouthpiece placement change, BUT since she's had the benefit of seeing you play and knows your playing, it would be very arrogant and unfair of me to disagree with her.

I think I know where this is coming from. I have a student that, when I first started teaching, played off center as well. That's not bad, but it is when it effects the rest of your playing. Off center is one thing, but it really can be too much. This student played waaaay off center, and as he got higher, he shifted out even further.

It will take time, getting used to this new position, but trust me, you will get used to it. That is more than likely the origin of the endurance problems. Just keep working at it, getting used to the new position, and it will all come around. Better to solve this issue now patiently than wait until it's too late.

I agree to what both of you said. I had a trombone day thing at the college where she teaches and I asked her. She just told me that were first going to see if I'm just worn out from playing almost none stop for the past 2 weeks. So this week is going to be lazy, not completely stopping, just not playing as much. But were going to see on that first. My mouthpiece readjustment is changing just fine thankfully. Slowly, but its getting there.
Thanks for your suggestions and comments, it really helps to know more of what could be happening if it not over working. Plus I can also help others with this later in life.

Thanks.