You are about to graduate uni....WELL DONE! It is not an easy feat and many, many people try and don't get through it so right off the bat you should feel very proud of your achievement. It wasn't easy and you deserve to accept that you have achieved a great goal! So, your next step may be side tracked but it doesn't mean you give up..... it means you dig down deeper and figure out what you have to do to get to your next step in life. There are many solutions you just have to take the time to look what needs to happen.
If you feel you are truly an alcoholic then you must seek immediate help!! Please seek help! You can begin with telling a medical doctor your concerns. Alcohol, as you already know, is no substiution for human contact and it will cause a great deal of unnecessary, avoidable drama that will have a long term negative impact on your life. It is not too late to turn your life around and lead a successful productive life but you must be willing to put the work and mental effort into getting sober. There is a lot of help out there. Are you in America now? If so there are many places to seek help.
As far as your social situation I feel if you could seek out a counselor that could let you vent your frustration and offer up helpful positive suggestions for improving yourself would be such a bonus for you. Don't worry about the 'stigma' of seeing a counselor....(as if there is a stigma).... SO MANY people see and benefit from counseling. Use it as a tool to help you socially and to help you sort out what you need to do for your next step in life. You already know you have an avoident personality. It is definitely hard for others to be your friend if you avoid the contact and interaction with them. Let a counselor help you learn how to work with your personaliyt type.
Get sober and stay sober. I know three very successful men who were alcoholics and chose to get sober. They used that negative experience and self-disppointment to grow stronger and as I said all three went on to become very successful men in business. FYI they all got involved and stayed involved in a AA Program. You have a lot of positives you can work to achieve going forward. It won't be easy but the outcome will be worth every bit of effort but YOU have to be the one who makes the change in your own life (with help). You've come here to TSR to ask opinions and vent and ask for some help. Go to the professionals who can actually help you to turn your life around. Best of luck!