Hi!
try going to http://www.meetup.com. search for a local mothers group near you (martinez). Don't let age be an issue, as those older mothers with older children been there to. Use them to pick their brains, get mommy support and who knows, they may even know of another young mom such as yourself.
Being young and having an unplanned pregnancy alone is pretty frustrating. You are adjusting to a whole new responsibility, that will be with you for many years to come. A part of you is still there, but pushed aside for a while.
Being a first time mom and in my early 30's, going through drama before, during and after the birth of my son and having only my mom for support, I had a rough time. Thankfully my son was the reason to smile every day. Sure, at times I would feel lonely but all that went away the minute I saw my son.
Try to make your little one your go to person. Yes I know the little one can't communicate they way you need. Maybe just expressing yourself to your baby can let some of your stress out. A minute to just breath. Take a nap with your little one to relax.
Try to just go outside and download when your little one is napping. Listen to music, play online, do something to help occupy your time. In between your little "free" time, focus on you. Take a bath. Or even a hot shower. Anything to just get away from it all, to recollect yourself.
Do know, you are not alone. Also don't let someone push pills on you, as pills are not your first answer. If you can recgonize the reason for why you feel anger, more than depression, then you can focus on fixing the problem, or helping it be less of an issue for you.
If you can have your MIL take her grandchild for a few hours to go have some you time. You need that time alone for your own santity, especially since you do have a newborn and i am pretty sure your little one isnt sleeping through the night. So your pretty tired. Which doesn't help with your anger. Your irritable. Frustrated. Grumpy! lol
What worked for me, as I stated before, was my son. Even though the drama around me was pretty intense, my son made, and still makes my life that much clamer, even when he is the reason for my frustrations. Its hard to stay mad at him, when he is my little angel and my little SONshine :)
Embrace your little miracle. try to see positive in your life and do know, only YOU can change your situation. Really think deep down about your own needs. Are they being met? Is your bf helping you with your little one? What can you do to help eliminate this frustration...maybe moving? Maybe seeking a counselor to just vent...someone who is bias. Its better than a pill :)
If you drive and have time, I am always looking for new mommy friends. My son is 14mo old but he loves the little ones. Just to even get away from your world over in the east bay helps. I can even refer you to a few of my friends in the east bay who have children. They are in their 30's but been there before.
Send me a message if interested. Oh also there is a place in San Ramon called Superfranks. Its a GREAT place to meet other new/young moms. I been there before with a new mommy friend I met (through myspace). Our kids are only 2 weeks apart. It was great to meet her, her kids and have a playdate.
Hope you find that happiness within! good luck to you, and I am serious about getting together. Just because I am in my 30's doesn't make me old :) i am young at heart. Plus I am always open to making a new friend.