Hey Alex, for a start you have come to right place here!
I'm 47 and came out to my wife of 20 years just 2 mths ago, after having some pretty low and dark thoughts. I wish that I had come out when I was in my teens, but didn't/couldn't.
Birdy has hit the nail on the head with Qlife - google them and call them (Also Birdy is awesome - has given me a lot of help and friendship on here over the last few months!!!). Qlife are open from 3pm to midnight everyday of the week, but note that they are a peer support phone help, and often you may need to try calling them several times until you actually get through. I had to call more than 6 or 7 times, but they are ace. They were recommended to me early on, and I haven't looked back.
Also as Birdy said, go to your Dr (or go to a LGBTI friendly Dr that Qlife can recommend near where you live/work), and ask for the Mental health care plan. This means that a good portion of psychologist fees are covered by Medicare.
And don't worry about not having a boyfriend yet! As mentioned, I'm 47 and haven't had one yet either!! I'm still living with my wife and kids, but looking at getting a place of mine over the next few months. I'm lucky, as my wife still loves me and has come to terms with who I am, and is supporting me.
And as far as being overweight - well all I can say is join the club! I am too, and it is hard to drop the weight I know! For me, when I was 15 I was skinny as a rake, and I am convinced that my weight issue is because of the secret and stress/shame/guilt I put on myself. I put on 6-7 kgs a year until I was about 24, and ballooned out to 166 kgs. Thankfully, I've dropped a lot of that over the years, but still very much overweight too.
I expect that now I have come out, and coming to terms with who I am, that I will lose some of the weight over time.
I recommend you go and find someone to talk to, to work through your feelings. You need to know that you are a GREAT person, don't let anyone else tell you otherwise.
Perhaps look at also joining some LGBTI groups and meeting people with similar interests. I don't know where you are located, but in Melbourne there is a whole heap of groups for LGBTI - google "team Melbourne" and you will no doubt find something to interest you. Something like the Melbourne Front Runners walking/running club - great way to meet people socially of all ages and fitness levels (and drop the weight!)
Anyway, take care mate. Remember you are GREAT!