As others have said, 'it depends' is the only answer to your rather vague question. You really should learn what it takes to keep a healthy horse, if you have one, and diet is a pretty major factor. Some basic principles...
*A horse should have no less than 1.5%bwt daily in forage. If they're an 'easy keeper', this may be well enough, fed in a 'slow feed' net to prevent gorging. If they're thin or in hard work, the amount of hay/grazing may need to be more like 2.5%bwt. Preferably low sugar grass hay, if there's no grass to graze. They should be fed this free choice, or at least little & often, as it's not good for horses to go hungry for periods between 'meals'.
*IF supplementary 'hard feed' is required because they're too thin or in hard work, then it's best to avoid grainy or otherwise high sugar/starch ingredients, and provide easily digested high energy feed like alfalfa, beet pulp, etc.
*Nutritional balance may not be up to scratch, depending on what's in the hay/grazing & other feed, but you need to know what they're getting, to work out what they may need to 'fill the gaps'. A high quality 'ration balancer' may do the trick, or you may need to provide certain 'custom blended' minerals & such to a small feed(or their regular feed if they get any).
She's had her teeth done, always been an easy keeper, she gets alfalfa hay from our local tack store and also Neutrena senior feed.
WHY are you feeding her straight(?) alfalfa as forage, and feeding her 'senior feed' if she is an easy keeper? Horses, as with people, dogs, etc, are not healthy if they're much overweight & overfed. Particularly if they eat a lot of 'junk food' - high carb diet.
She gets four flakes of hay and 9 qts of feed a day.
A 'flake' & a 'quart' are rather ambiguous. You need to work out how much she's getting in weight.
I can only let her out for any period of time if I can stay with her for however long, so she's become somewhat barn sour, ... Everyone says I need to give her up, but I love this little horse,
You also need to understand that it is not good for their health & wellbeing to keep them cooped up & unexercised all the time. I am NOT saying that you SHOULD give her up, and I would not worry about what 'everyone' says, but if you love her so much, you will want what's best for her, and if after learning what that entails, if you find you cannot provide it, it would be only fair to rehome her to someone who can look after her properly.