very different high each time

so I made some firecrackers about 3 weeks ago (will eat the last one later today). I only had one other proi edible experience which was mild and we were also smoking and I felt it didn't hit me till I got home. which makes scene from what i've learned here- they seemed to think you'd fell it in like 30 min. any way so I've eaten 4 -no exact amout known cause I have no scale yet (hopefully get one later this week) but started small. first time after a 5 month break was the strongest and parts unpleasant waves. next one similar but better. the last 2 time was peices of the firecracker I thought was medium amount of weed but I felt much less both times I went out after eating it and the one didn't feel much till 4 hours. Now this is ok because I do sometimes want to not feel that stoned. tonight I'm going to eat a bigger piece of what had the most weed. but i guess what I'm asking is how to help determine the high level. when i get a scale is it good to pre messure what is going on each cracker? where i ground it all and sprinkled it on estimating- some got more -some got less. I'd really like it if I could make different ones if I wanted to go out and stronger ones for staying in. hope that made some scene.