2.6 year old picking up on stress?

[SpanglyGiraffe]

I'm say here crying & feeling completely crap after I've just taken my DS to toddler group. Wel left after 15 minutes as in that time he pinched a baby & bit another toddler.
He went through a phase of doing this when he was 1, and I felt like I never wanted to take him out ever again. Eventually with the help of fantastic friends who had all been through similar things with their DC's he grew out of it. I made sure he saw friends all the time & he was going to nursery.
This year I've become a full time carer for my mum, and the friends I saw last year have had their own problems & we've all drifted a bit.
DS doesn't go to nursery anymore as I stopped working to look after my mum so couldn't afford the nursery fees. He stills sees friends but not as often as he did. These last few months my mum & I have have been trying to sell our house & it's been very, very stressful. I've made sure I've been focused on my DS, and have been taking him out every day. Park, soft play, library, groups etc.
But he is just a NIGHTMARE. He's been biting & lashing out at me for months. I used the "naught step" for a while but he wouldn't take it seriously & we'd both get wound up, so I've stopped it. Now I tell him "No" and then ignore him, which admittedly is working a bit. But i'm still covered in bite marks all the time!
What can I do?? Right now I feel like I'm back in that place again where I never want to take him to a group again. I usually helicopter him like mad, which I know is necessary to stop him hurting others, but u just can't face ever going again! I'm assuming this had stemmed from picking up from the stress from my mum & I? What can I do to help him? We're looking to move now in a couple of weeks, (DS, my mum & I all live together & will be moving to a new house together) and I know that things will be a lot less stressful for all of us once we have moved. I try & stay calm around DS all the time & to not come across as dressed but it's do hard sometimes.
Does anyone have any magical tips as to how I can stop this behaviour?
Sorry for the long ramble, i don't want to drip feed. I'm on my phone too so sorry for any
mistakes.

It really does sound like your having a tough time, and kids do pick up on stress and no matter how much we try and do nice things the can just rebel and behave like that, when me and my daughters dad split i had the same problem, she was 18 months old and would scream and tantrum, bang her head against the bars on her bed and wouldnt sleep properly, but it does improve.
I know when they behave like this you feel like you dont even want to leave the house and you feel other people are judgeing your childs behaviour but staying inside will make YOU feel worse. try takin him somewhere with lots of grass where he can run off energy, watch what hes eating because im not sure about other mums but ive noticed even things like fresh orange juice send my daughter wild! she wont listen 2 a word i say, and just as importanly make some time 4 yourself and try and unwind, even if its just a nice hot bath and a glass of wine in the evening. i hope this makes u feel better x

Thanks very much I'm feeling a bit better about it now. It really is awful when they misbehave but i keep telling myself it WILL get better!
I'll keep an eye on what he's eating as well, that's definitely worth doing.
I'm going to take him to the beach tomorrow so hopefully the fresh air and space will do him good and he won't be able to get into too much trouble!
Thanks again