Happy Early birthday!

And congratulations for starting P90X, Great gift to yourself!
All the goals you mention are very possible! Follow the program, trust the program. You can do it. I know those self esteem issues...I have those. I hit a high of 215 pounds...215 extremely out of shape pounds! And I did just what you're talking about. I started P90x and lost 20 pounds and I stopped. I have no idea why, because I certainly wasn't happy with my body by then but those self esteem demons were screaming "you lost 20 pounds, big deal you won't lose anymore!". So i gave in. I got back to 209lbs before i decided to commit this time. less than 3 weeks to go before i finish my full first round! I've lost 25 pounds to date this go round

They key to my success on pushing forward came from outside support. I have my amazing coach who backed me up 1000% and i attribute a lot of my success to him. We have these forums for support, millions of people are behind you. We want to see you succeed and watch you're progress. It's like addictive to us!
As far as missing workouts go, I had a HARD time accepting this at first. I missed a day and was ready to just give up. Mad at myself, everyone around me..the world. But you have to look at it this way. P90X and these beachbody programs that are here for us to use to adapt into our individual lives and bring us success. If you miss a day, you have options to "make up" or you can look at it like this; your fitness and health isn't 90 days, it's the rest of your life. So you miss a day or two, in the long run that day or two will be ok! I have 3 kids, Life happens..they get sick, other responsibilities I have to do or i'm just plain exhausted. What did i do? I followed a rule, if i missed more than 3 workouts a week, i extended that phase by a week. As it stands , i should have been done with p90x this week, but i have 2 more to go! Then a week break and i'm after it again

Anyways, all that being said. Keep your chin up. Go push play and bring it. If you feel you need motivation, come to these boards, look at other peoples stories. Post any questions or concerns you have and let us answer them or come give you a boost. And my inbox is always open if you need anyone to talk to.
Good luck, looking forward to seeing your progress