I'm a young mum in my early 20's my baby is 14 months old 

I've been having these symptoms for around 12 months now and my gp seems to be always fobbing me off. Basically its lower back pain,bloating and pain in my lower left and right abdomen. The pain can go from dull and achy to a sharp stabbing pain where I literally can't stand with the pain. The bloating sometimes gets so bad I look 4 months pregnant (I'm of a petite build so its quite noticeable) . My periods is all over the place ranging from every 5-6 weeks to every 2 weeks. I'm also experiencing constipation which I've never suffered from before this. Sometimes during or after sex I get cramps. After countless visits to my gp and asking him to try something because this is not normal its effecting my everyday life he referred me for a transvaginal pelvic ultrasound which came back clear.So right now I feel like I'm going crazy thats it all in my head and its actually been getting me quite down and depressed where I dont even want to get out of bed somedays. He has now referred to a gynecologist but was told I could be waiting 6-12 months for an app. I'm basically just looking for some peace of mind wondering if anyone has experienced these symptoms or if there could be something that didn't show up the scan,is it something completely different wrong with me or is it all in my head ?