You really seem to have it all planned out well - which I think is the key to a beautiful low budget wedding. DIY helps to, and its great to hear you're getting your MIL involved too.
Have you considered asking friends if they know anyone who takes photos or does videography professionally? Usually a reference from a friend can save you heaps of money.
Another good way to save money is having a lunch time reception or Friday/Sunday evening instead of Saturday. Another key tip for saving money at the reception is to talk with the reception manager about tailoring a package to specifically suit your needs.
My venue offered 3 courses of three different meals which made the cost per head very expensive. After talking with them though I managed to get the price down to $58/head by having a choice of two entrees served on a fifty/fifity basis followed by mains again served on a fifty fifty basis. Then we will cut our wedding cake which will be served with ice cream and chocolate sauce as the dessert. Their drinks package was also more than I believe necessary because the venue is a little out of the way of most of our guests; so there are going to be a lot of designated drivers. I decided to put a tab on the bar to a certain limit for beer, wine and soft drink only; giving the guests the option of buying their own spirits and saving us a bundle. I've heard of other girls buying their alcohol from discount liquor stores which are also able to estimate the rate of consumption for your number of guests to tell you exactly how many bottles and of what you should have.
Since you are wearing a cocktail style dress perhaps you could consider having a cocktail reception. Again through negotiation you can tailor a package to suit your taste. It doesn't all have to be hor derves, you can have standing cocktails which are like small meals that can be eaten whilst standing like salads, soups, stirfrys and mini wood-fired pizzas etc. Much cheaper than having sit down meals and much more filling than your plain appetisers.
