Calorie Confusion

Hello all! I just joined this site, and after being just an internet onlooker on many other discussions I decided to join so that I could personalize my own question! SO I am: 6'1", female, 18 years old, 140 lbs. and am SO confused as to how much I should be eating a day. Just a little background real quick, I'm trying to lose 5-10 lbs. (Ideally would LOVE to be 130, but will settle for 135 if I start looking too gaunt/emaciated), I workout 5 days a week, always varying my workouts (swimming, spinning, weights, stairmaster, ellipticals, blah blah blah) so burn maybe 500-600 a day. On my off days I'll walk 6 or so miles down the beach. I don't log my cals on this site or anywhere, I just estimate them. I'll visually determine calories of things like nuts, chicken, rice, etc. So I'm never 100% sure how much I should eat a day, but I think I work it out pretty well in my head, and its usually around 1300, give or take 200 (1100-1500). Maybe twice a week though, like today, I'll be a bad girl and eat like 1800 (and feel really ****ty and guilty, but my body wants it, and I heard that occasional things like this boost weight loss/metabolism so don't feel AS bad). I know it may sound extreme having nets sometimes in the high hundreds or low thousands, but because I'm trying to lose such a small amount of weight and am not heavy to begin with I feel like I need to take such measures to see results. Oh and by the way, I eat Paleo because of my dairy, gluten, and egg intolerances (and by choice avoid soy and red meat ~ ). So if I don't know/can't pronounce the ingredients, I don't put it in my mouth. BUT I have IBS-C (which is a real beotch) so I had to add rolled oats and brown rice to the Paleo lifestyle for some soluble fiber and for something nice and gentle on my stomach. Along with a daily dose of miralax and probiotic. Anyways point being I live an extremely healthy lifestyle but just don't know how much I should be eating and if I am going about this whole thing the right way! At my current rate I'm losing a pound maybe every other week. Should I be eating like other regular women, or because of my height should I eat more like a guy? There's not many women like me, so its hard to find answers because they're all geared toward average women, and I am far from the average woman. Another thing, I am ALWAYS TIRED and recently I am always hungry too, thats why I ate so much today, I couldn't take it anymore. I wake up tired, and it pretty much lasts throughout the day. As I write this I am tired and hungry and could easily eat dinner #3 (yes~ I was so hungry I ate dinner before workout (5 p.m.) and after workout (8:30 p.m.) And I drink 13 glasses of water a day. OH and last thing (promise!) I haven't gotten my period for 6 or 7 months (since Christmas) which should be concerning but honestly I don't mind (no PMS/bloating./cramps). So anyhow I send 100% of my love to anyone who has any input on the matter, I thank you in advance!
~ Julia xoxo