Pinkbubbles, you really have my sympathy.
It does get easier, I promise.
It is hard to be alone with a baby - I'm a stay at home single mum so do it all day every day and, much as I love DS, sometimes it is sooooo hard. I'm sure I shouldn't admit this on here, but I went through a phase of nodding off on the sofa when DS was playing on the floor... I felt like an awful mum but he was in a baby-proofed room and was quite safe. I knew I couldn't keep on like that though and, over time, things got better. I saw my GP (I realised I was starting with depression) and got help for that and made a HUGE effort to get out and do things.
I am sure you are doing it, but if you have to nap when DS is with you, make sure he is somewhere safe. Is there someone else who can help you out?
I know it is hard when you are so exhuasted, but eating properly will help... do you take vitamin supplements?
Once your DS starts walking and taking 1 nap, your life will be much easier. And when he starts to talk, things will improve again. I find it much more rewarding (although more tiring) interacting with a busy toddler than a little baby.
Things I do with DS (to keep myself sane as much as for his benefit):
Playgroup
Drop in center
Walk to the park
Feed the ducks
Music class
Walk (almost every day, often with no destination in mind)
Swimming
Trip to library/ borders
Story time at the bookshop
Playdate at home or a friend's house
Museum (on a free day)
Zoo
My DS went in the baby swings (bucket type) from 4 months old - he was quite comfortable... If you have baby swings near you, maybe you could put him in one of those. Or hold him on your knee while you have a go on a swing yourself - you might enjoy it!
Are there any MNers you could meet up with?