i believe you're an ectomorph like me which mean you have very long arms and always been lean. you burn fat like crazy and you have an amazing metabolism. but when it comes to gain weight, urgh it's quite depressing.
about 6 months ago, i stopped listen to any personal trainer and stopped going to the gym because those PTs overtrain me when they know nothing about my body type. trust me. they're not born an ectomorph.
our body type is very different. you can eat the same amount of a guy 2 times bigger than you, but you'll burn all those fat before they do. it results in them gaining fat easier than you. when they workout, they easily transfer them greasy fat into muscles, not like us. T doesn't make you gain much muscles, but it helps you a lot if you start exercising. it'll be easier to build and maintain muscles. like just a little stimulation and voila, muscle. lol.
i find that if you don't have any fat, it's way harder to build up yourself. you'll just end up getting yourself so toned, 6 packs and all, but with tiny baby arms.
i have a calories counter app and i have to eat about 2050 calories daily which is kinda like a military base diet. even though i end up go over it like 2100, 2200. and those military guys workout and burn about 1500 calories daily so that isn't much compared to them. it's not about eating much, it's about how much calories can you eat? lol. you can eat lots, but those food are very low in calories, and it results in your body type burns all of them, and fast. 2700 is way too high, you may find it very comfortable trying to force yourself too much ;o
so keep that in mind, i started to ditch every gym personnel i know and change my own diet, force myself to eat way more than i could and about 5 times a day. all the high calories stuff. within 6 weeks, i gained 8 pounds, consistently. that's a lot to a skinny guy who finds it hard to gain weight to be honest.
then my appetite started to kick in and my stomach capacity grew in the process as well. which make me eat more, and feel ok and enjoy eating, rather than feeling like a stuffing duck in the past 6 weeks. it was worth it. now i can do more arm exercises and transfer those fat into muscles easily.
don't let the idea of gaining pounds is equal to getting back to the feminine body like you used to. that never happened. because you're on T, your body is distributing fat differently than it used to. now if i gain any weight, it goes straight to my belly, not my butt, nor my hips. it makes it really hard to have some abs. lol. but i mange to get my arms bigger than they used to be and it helps lots with dysphoria. i just have to work 2 times harder to burn my stomach fat and build abs at the same time. but no pain no gain :]
also, try to hop for weights rather than reps. you'd want to do more weights, that you can only do 4 reps and your muscles can't even do it on more time. then do lower weights, with 8 reps and change into some other workout before you injure yourself ;o and do it 3 times a week, you need to let your muscles rest, they'll build themselves up. you don't want to overwork yourself and burn all the calories you just eat. that's pointless to me. good luck man

keep us posted.