Firstly congratulations for persevering! If I had a pound for every time I threatened to give up on breastfeeding I would be a rich woman! My beautiful little girl is now 14 weeks old and breastfeeding her has not been easy to say the least.
Ask your health visitor if there is a local breastfeeding support group. ? I attended my local group for a very similar problem and found it invaluable.
There are some really good websites and telephone helplines. I can recommend the Breastfeeding Network site and their helpline is excellent
http://www.breastfeedingnetwork.org.uk/
Just like Natalie and yourself I too struggled with expressing - I tried an electric and a manual pump and could only get about 2oz a day. I gave up expressing. Now, I get Daddy to give bubs a bottle of formula milk at bedtime. This was a really hard decision to take, but, I am so glad I did.
Good luck xx