I'm a SAHM to a 2 year old. Personally I love it, but it can definitely be hard work! Try to get as many regular groups as possible, organise playdates with other mums and alternate weeks for whose house they are at, go to the park if the weather is ok (we have been known to go even in light rain - just stick a puddle suit on and take a football so they aren't slipping off the play equipment). Try to get out and about at least once every day, ideally both morning and evening.
Make a mental list of the activities that your DD enjoys playing alone (my DS plays with his cars, little people sets, noisy/tactile books, colouring with crayons etc). These are your lifeline to be able to get any housework done, drink a brew in peace etc.
Make another list of guided activities she likes. For my DS this is things like play doh, counting the change in my purse, painting, baking, reading together etc. Try to do at least one or 2 of these things each day. My DS is gradually getting a longer attention span, but I just accept that if he's bored of something then we just pack it away - I don't try to make him keep playing.
We try not to have the tv on a lot - I don't watch anything during the day and I only let DS watch a little in the morning and he watches a bit while I make his tea (easiest way to keep him out of the kitchen :) ) but some days I need to let him watch a bit for my own sanity if I'm tired or unwell. I don't think there's anything wrong with this as long as its not every day.
Sorry, this was a very long winded way of telling you to fill your days and have some structure each week 