Fed up of constant mood swings. Depressed/extremely happy

Got to the point of being fed up of my constant mood swings. For the past 4 years they've gotten worse. When I'm in my low mood, I hate myself completely - I won't go out in public due to the fear of being stared at, I get major anxious and hide myself behind thick hoodies, hood up staring down, I don't want to be around people, I'll find any excuse to not, I drink heavily to attempt to sort myself out - it never works, I can drink around 7/8 bottles of wine a week but end up breaking down major and crying uncontrollably in front of friends if I'm around them. This is the point where all my dirty laundry comes out and then I get judged and then they don't want anything to do with me. I constantly eat, which makes me hate myself further due to weight gain, I'll feel constantly tired, I'll climb in bed unable to sleep for hours due to over thinking depressing things, I'll finally sleep just to sleep for 12-15 hours and then feel tired still.

Then there is when I'm extremely happy.. I'll be running around the place, fidgety, forgetful, talk too fast, laugh uncontrollably over nothing, I can occasionally think things are happening when there not, I sometimes hear my name being called when theres no-one around me, I feel like I'm 'losing the plot' cause I'll put something somewhere, my thoughts are too busy racing, I'll run off quickly to do something then I'll come back for it but forget where I put it then I start getting increasingly irritated and aggressive. I'll then find it and snap back to being majorly happy. I'm incredibly sexually active when I'm in my 'high' mood. I also drink uncontrollably to try and 'calm' myself down, but I too can drink 7/8 bottles of wine a week when I'm in my 'high' episodes, this is when I either get aggressive/violent when drunk or can occasionally cry but I'd get up and run off as if nothings happened. This is the drunken phase where I end up losing friends and I'm at the end of my tether. I also spend too much money on things I don't need, this is the mood I end up spending money on alcohol (even after drinking 2/3 bottles of wine one night ill go out and buy even more, most I've spent out is 80£) which hasn't helped my financial situation as I'm at university..

I can't handle being so up and down all the time. I've never had a normal day where I've not felt extremely happy or extremely emotional and down in the dumps. My highs can last 1-3 weeks and my lows 4-10 weeks. My longest high was about 6 weeks where I did some crazy regretable things which doesn't help when I'm down as I end up getting extremely down about it all when I enter my depressive state.

I finally confessed to my sister in law about everything and shes forcing me to seek help as I always refuse too as I see my alcohol abuse as my form of 'self medication'.

Has anyone else ever had similar issues and what happened when you finally went to the GP? I'm too embarrassed and worried of judgement so need some encouragement..