Please please don't feel ashamed.. there is no room for shame with living with this condition, you are doing an amazing job without realising it, HbA1c's/graphs are not a target to define yourself by, they are diabetes tools which can help steer us, so try to detach your emotional attachment from them, they act as information only. We can all do more, seriously there is no such thing as perfection with managing this condition.
Firstly contact your DSN and get some support from them, sometimes it helps to sit down with someone and analyse what works and what doesn't, show them your graphs, try and work out where and when you are having issues ? Could a change in insulin help, can they help with a course ?
It's easy with this condition to focus on the negative, but try and think of 3 positives of where you manage well and write them down.
Personally for me I find exercise after eating helps manage a spike, I can't sit still after eating, I get up, walk, do gym or something which stops the arrow heading north, I eat low carb at certain times of the day when I know my insulin doesn't work as effectively, I aim to sleep every night with a stable line so avoid eating late, avoid high fat meals which stops the spike later on, if I want cake I eat it, but bolus in advance and exercise after.
Well done for asking for help, don't beat yourself up though be your own best friend and be kind to yourself, we can help too.