Help lol I am so lost

So my boyfriend and I have sex regularly or at least try to and I am on the nexplanon thing in my arm and I havr been feeling so weird lately and everyone has been asking/assuming that I am pregnant and I have been gaining weight and eating like a pig and feeling super nauseous and I have been super irritable and I have the shortest fuse now that I could snap in a second and my boyfriend has even asked me if I am pregnant and I don't know what to do cause I have no idea how I am feeling anymore and I never get my period and haven't for a while like since I was 16 so I don't know what to do cause I feel so weird and I also have been feeling like I am getting punched in my stomach lately and I feel like my stomach has gotten bigger and I have felt like I am so out of breath like I hate standing up anymore cause of the feeling of that and I don't know what to do cause if I take a test if feel like it would be negative because of the nexplanon and I would have no idea what the truth would be and I don't have any money to get a test and the thing on here said that I am 100% on everything and our puppy has been getting more and more attached to me and I don't know what to do so someone help me lol I have no idea what I am feeling