Been thinking of you mrshope. So sad to read what a tough week you've been having. Gosh I could have written all the things you wrote as I felt exactly the same. On a few of his most unsettled days I wondered if I'd ever be a happy or be a good mum. I felt like I was letting my DP, family and DS down as I was finding it so hard. I see now that of course that wasn't true but at the time I just felt so overwhelmed.
It's great that your doctor has prescribed Ranitidine so give it a few days and see if it helps ease things a little. There's lots of great advice from Mumsnetters about reflux on the health boards.
Do go out and see people too, even if you feel a bit embarrassed or stressed by your baby's crying. Nobody minds as they've all had their moments. Maybe go along to a breastfeeding group or baby café as you'll meet some sympathetic mums and more experienced mums too who will be able to reassure you. Also bear in mind that all babies have their challenging phases. At first my DS was the hardest baby in my NCT group by far - he was almost never awake and content for more than a moment or two - but in the nine months since each of the babies has given their mums a difficult patch. It might come at teething or crawling or weaning or naptimes but it happens now and then. So brave the outings or perhaps suggest to just one or two mums that you could have a walk in the park or a cuppa at home together or baby cinema where the noise of the film will take over any grizzling!
It is so exhausting though, isn't it? And being tired is just horrible as it makes you feel all at sea, really upset and cross. Don't feel guilty for having to have a little break sometimes - whether that's two minutes in the loo or ten minutes peace and quiet whilst someone else holds him - as it's really important to look after your own health too, mental and physical. My mum used to hold him for an hour for a nap whilst I walked the dog by myself or had a quick cuppa with an old friend.
As for sleep then I'm afraid my only advice is just hold on in there for a bit longer as he's still really tiny. My DS had pretty much all his naps in the sling/my arms and then gradually the push chair for months. It was pretty intense as you don't get a break but it was the only thing that worked. I watched a LOT of Netflicks! At six and a half months (when I got a cold and couldn't go out with the pram) we used the No-Cry Nap Solution to get him to nap in his cot. It took a good few weeks and the naps were short at first but one day he rolled onto his front to sleep and started having good 1 1/2 hr naps in the morning and at lunch. There was nothing I did differently (and believe me I thought I'd tried everything!!), he was just ready.
And please please don't think that you're letting anyone down. An unsettled baby is such hard work and it's so upsetting when things aren't as you dreamed they'd be. Hold tight and keep strong and one day (in hopefully the not too distant future) you'll be playing with your baby or laughing with them and it WILL be just as you dreamt it would be.
Take care and keep us posted on how you're getting on. xx
PS Sorry for the long ramble! Naptime so I'm trying to multitask!! x